xilinx: common: Add support for SOC detection

xilinx: common: Add support for SOC detection

Code supports board detection based on information available in EEPROM in
legacy or FRU format. But this is not enough for emulation and simulation
systems which are lacking these identification EEPROMs. But SOC itself has
normally registers for SOC identification. Based on them it is possible to
compose detected name. That's why prepare infrastructure in common location
for SOC platform detection which is called before board platform detection.
SOC platform detection shouldn't detect real silicon and should fallback to
current existing mechanism to identify boards based on EEPROMs.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/329a8da338927b082e26a958bf69bb18af072420.1662460837.git.michal.simek@amd.com