400G-ZR: Allow all configurable laser frequency for coherent modules

[jaganbal-a]

Problem description:
At present only 75GHz grid frequency values are allowed for configuration (75GHz grid is hardcoded).
https://github.com/sonic-net/sonic-platform-daemons/blob/master/sonic-xcvrd/xcvrd/xcvrd.py#L1295

Any other frequency value configuration lead to xcvrd child process to crash due to exception raised by current code if the value is out of range or other than 75GHz grid channel frequency.

All the module capable frequency should be allowed for configuration/programming and any frequency which the module is not capable of should be rejected by the CLI.