drm/amdgpu: return -EFAULT if copy_to_user() fails

If copy_to_user() fails then this should return -EFAULT instead of
-EINVAL.

Fixes: c65b0805 ("drm/amdgpu: RAS EEPROM table is now in debugfs")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>