media: aspeed: fix an incorrect return code on buffer allocation failure

It returns '0' even when a failure happens on jpeg buffer allocation
so this commit fixes the issue.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>