[media] media: vb2: fix handling MAPPED buffer flag

[media] media: vb2: fix handling MAPPED buffer flag

MAPPED flag was set for the buffer only if all it's planes were mapped and
relied on a simple mapping counter. This assumption is really bogus,
especially because the buffers may be mapped multiple times. Also the
meaning of this flag for muliplane buffers was not really useful. This
patch fixes this issue by setting the MAPPED flag for the buffer if any of
it's planes is in use (what means that has been mapped at least once), so
MAPPED flag can be used as 'in_use' indicator.

Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Pawel Osciak <pawel@osciak.com>
Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>