misc: amd-sbi: Add document for AMD SB IOCTL description

misc: amd-sbi: Add document for AMD SB IOCTL description

- This document provides AMD side band IOCTL description defined
  for APML and its usage.
  Multiple AMD custom protocols defined for side band system
  management uses this IOCTL.
  User space C-APIs are made available by esmi_oob_library [1],
  which is provided by the E-SMS project [2].

Link: https://github.com/amd/esmi_oob_library
Link: https://www.amd.com/en/developer/e-sms.html
Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
Link: https://lore.kernel.org/r/20250428063034.2145566-11-akshay.gupta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>