Add SAMD5x/E5x and all missing SAMx7x devices

[chris-durand]

• Add SAMD51 / SAME5x device family
  • UART
  • Clock
  • USB
• Add SAME54 Xplained Pro board with blink example
• Rename UART drivers
  • sam -> sam-sercom
  • samg -> sam
• Improve support for SAMx7x device family
  • Add UART / USART
  • Add SAMS70, SAME70, SAMV71 devices
• Fix data reception in the SAMx7x and SAMG UART driver
• Add SAMV71 Xplained Ultra board with blink example
• Refactor GCLK driver
  • Expose flexible clock generator / clock source configuration in API
  • Remove hardcoded assumptions of available clock sources
  • DFLL48 configuration
  • DPLL configuration with automatic coefficient calculation
  • API to enable peripheral clocks
• Fix selection of device headers. In some cases headers belonging to the wrong device variant were chosen.
• Adapt family naming scheme
  Not all devices which belong to one logical family share a common name prefix (e.g. the E70/S70/V70/V71 device family). The identifier scheme is changed to

  {platform}{series}{pin}{flash}{variant}-{package}{grade}
  

  and families are assigned based on logical grouping and not by name prefix.
• Hardware test
  • SAMD21 Xplained Pro
    • UART
    • GCLK
      • DFLL48 open-loop
      • DFLL48 closed-loop
      • DPLL96
      • OSC8M
      • Peripheral clock configuration
    • USB
  • SAME54 Xplained Pro
    • UART
    • GCLK
    • USB
  • SAMV71 Xplained Ultra

SAMx7x have both UART and USART peripherals with the same id. The driver is adapted to provide :platform:uart:* and :platform:usart:* modules. This driver is also shared with the SAMG devices. For implementation simplicity and consistency I have changed the SAMG USART peripheral to also use the :platform:usart module and naming (see this commit). This is a breaking change. Would that be fine with you @mcbridejc @salkinium ?

I have also renamed the previous "samg" UART driver to "sam" because this one is used by all SAM devices without SERCOM peripheral. The SERCOM based driver driver is renamed from "sam" to "sam-sercom". That renaming is a bit too much for github to display correctly in the diff.

[chris-durand]

@salkinium In a lot of places we are making the assumption that device families have unique device name prefixes. For SAM this is not true, e.g. SAMD51 and SAME51, SAME53, SAME54 are a device family as well as SAME70, SAMS70, SAMV70 and SAMV71. This makes the family field of the device identifier a lot less useful in the driver implementations. Can we live with it for now?

[chris-durand]

The auto-generated HAL matrix table makes not much sense anymore with these devices added. The shown device families are D21, E, G55, S, V70.

[mcbridejc]

This is a breaking change. Would that be fine for you?

That's fine by me.

[salkinium]

Do you already want review feedback at this point?

[chris-durand]

Do you already want review feedback at this point?

I would appreciate a first review. Keep in mind that I haven't updated the PR description yet. There is a lot more stuff in there than mentioned.

[chris-durand]

Just FYI, the diff does not correctly show that in this commit the uart drivers have been renamed. It might look like entirely new code in the diff but it isn't.

[salkinium]

Thanks a lot! I will merge this at the latest tomorrow together with the modm-devices PR and update the Q3 release.

[salkinium]

@rleh do you still want to review this PR?