drm/exynos: gsc: Handles the combination of rotation and flip

The unique results of all the combination of rotation and flip can
be represented by just 8 states. This patch handles all the combination
correctly.

Signed-off-by: Hyungwon Hwang <human.hwang@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>