fpga: xilinx: Add option to skip bitstream ID check

fpga: xilinx: Add option to skip bitstream ID check

Add environment variable 'fpga_skip_idcheck' that when set to '1' or
'y' allows bypassing the device ID validation during bitstream loading.
This is useful for loading bitstreams on devices whose ID codes are not
yet recorded in the SOC driver.

Usage: setenv fpga_skip_idcheck 1
  fpga loadb 0 ${loadaddr} ${filesize}

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/d0f11d0a8d48b284683f00d20dfbe323c11f2943.1776360720.git.michal.simek@amd.com