media: staging: ipu3-imgu: Move alignment attribute to field

Move the alignment attribute of struct ipu3_uapi_awb_fr_config_s to the
field in struct ipu3_uapi_4a_config, the other location where the struct
is used.

Fixes: commit c9d52c11 ("media: staging: imgu: Address a compiler warning on alignment")
Reported-by: Tomasz Figa <tfiga@chromium.org>
Tested-by: Bingbu Cao <bingbu.cao@intel.com>
Cc: stable@vger.kernel.org # for v5.3 and up
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>