[media] m5mols: remove union in the m5mols_get_version(), and VERSION_SIZE

Remove union version in the m5mols_get_version(), and read version information
directly. Also remove VERSION_SIZE.

Signed-off-by: HeungJun, Kim <riverful.kim@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>