RAS flags needs to be cleaned as well when user requires
one clean eeprom.

v2: RAS flags shall be restored after eeprom reset succeeds.
Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>