[SRU][F:linux-bluefield][PATCH v1 0/1] UBUNTU: SAUCE: mlx-bootctl: rshim logging display from linux sysfs

[Liming Sun]

BugLink: https://bugs.launchpad.net/bugs/1927263

SRU Justification:

[Impact]
* N/A.

[Fix]
* Add support to display rshim logging bufferthe check properly to make sure the buffer won't wrap-around.

[Test Case]
* cat /sys/bus/platform/drivers/mlx-bootctl/rsh_log.
  Example:
      cat /sys/bus/platform/drivers/mlx-bootctl/rsh_log
       INFO[BL2]: start
       INFO[BL2]: DDR POST passed
       INFO[BL2]: UEFI loaded
       INFO[BL31]: start
       INFO[BL31]: runtime
       ...

[Regression Potential]
* SQA has regressioned the driver with this change and didn't find any new issues.