media: staging: imgu: Address a compiler warning on alignment

Address a compiler warnings on alignment of struct ipu3_uapi_awb_fr_config_s
by adding __attribute__((aligned(32))) to a struct member of that type as
well.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Rajmohan Mani <rajmohan.mani@intel.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>