media: stm32-dcmi: drop unnecessary while(1) loop

The while(1) is effectively useless as all possible paths within it
return thus there is no way to loop.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>