media: v4l2: move compat handling for v4l2_buffer

The ioctl commands based on v4l2_buffer have two sets of compat calls,
one for native time32 structures, and one for compat structures on
64-bit architectures.

Change the compat version to use the same approach as the other simpler
one, for both versions of the structure.

In an earlier version of the patch, I unified the v4l2_buffer_time32
and v4l2_buffer32_time32 compatibility handling into a single
implementation, but that relied on having it all in one file, rather
than having the in_compat_syscall() version in v4l2-compat-ioctl32.c.

[hverkuil: fix various trivial checkpatch issues]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>