media: ar0521: Fix return value check in writing initial registers

The return value from register writes is ignored apart from the last
value. Fix this.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>