media: atomisp: remove useless returns

Returns are not useful at the end of void functions,
they can simply be removed.

Link: https://lore.kernel.org/linux-media/23a6984ddfb15ba38f6983381bb6fdaef3edd7d8.1620479607.git.paskripkin@gmail.com


Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>