media: platform/sh_veu.c: remove redundant NULL pointer checks

Function `sh_veu_find_fmt` returns an address that is an addition of a
base pointer `sh_veu_fmt` and an offset. The base pointer refers to a
global variable of which address cannot be NULL. Therefore, this commit
removes the NULL pointer checks on the return values of function
`sh_veu_find_fmt`.

Signed-off-by: Shaobo He <shaobo@cs.utah.edu>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>