[media] v4l: vsp1: Don't sleep in atomic context

The vsp1_entity_is_streaming() function is called in atomic context when
queuing buffers, and sleeps due to a mutex. As the mutex just protects
access to one structure field, fix this by replace the mutex with a
spinlock.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
(cherry picked from commit adb8963f

)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>