Before uninstalling gpu driver, flush all cached ras
bad pages to eeprom.

v2:
  Put the same code into a function and reuse the function.
Signed-off-by: YiPeng Chai <YiPeng.Chai@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>