media: vb2: replace bool by bitfield in vb2_buffer

The bool type is not recommended for use in structs, so replace these
by bitfields.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>