[media] s5p-mfc: Fix initialization of internal structures

Initialize members of the internal device and context structures as early
as possible to avoid access to uninitialized objects on initialization
failures. If loading firmware or creating of the hardware instance fails,
driver will access device or context queue in error handling path, which
might not be initialized yet, what causes kernel panic. Fix this by moving
initialization of all static members as early as possible.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>