Fix value of SYSINFO_SOC_IO_ONEWIRE in NEORV32_SYSINFO_SOC_enum

[tmeissner]

It seems that there was a copy/past error when onewire unit was added to the NEORV32_SYSINFO_SOC_enum:

enum NEORV32_SYSINFO_SOC_enum {
...
SYSINFO_SOC_IO_XIP         = 30, /**< SYSINFO_FEATURES (30) (r/-): Execute in place module implemented when 1 (via IO_XIP_EN generic) */
SYSINFO_SOC_IO_ONEWIRE     = 30  /**< SYSINFO_FEATURES (31) (r/-): 1-wire interface controller implemented when 1 (via IO_ONEWIRE_EN generic) */
};

This PR corrects the value of SYSINFO_SOC_IO_ONEWIRE to 31.

Please close this PR if this is by intention.

[stnolting]

You are right! Thanks for finding and fixing! 😉