[media] exynos4-is: Remove redundant module_put() for MIPI-CSIS module

Currently there is unbalanced module_put() on the s5p-csis module
which prevents it from being unloaded. The subdev's owner module
has reference count decremented in v4l2_device_unregister_subdev()
so just remove this erroneous call.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>