[media] gscaler: Add new driver for generic scaler

This patch adds support for G-Scaler (Generic Scaler) device which is a
new device for scaling and color space conversion on EXYNOS5 SoCs. This
patch adds the code for register definitions and register operations.

This device supports the followings as key feature.
 1) Input image format
   - RGB888/565, YUV422 1P/2P, YUV420 2P/3P, TILE
 2) Output image format
   - RGB888/565, YUV422 1P/2P, YUV420 2P/3P, YUV444
 3) Input rotation
   - 0/90/180/270 degree, X/Y Flip
 4) Scale ratio
   - 1/16 scale down to 8 scale up
 5) CSC
   - RGB to YUV / YUV to RGB
 6) Size
   - 2048 x 2048 for tile or rotation
   - 4800 x 3344 other case

Signed-off-by: Hynwoong Kim <khw0178.kim@samsung.com>
Signed-off-by: Sungchun Kang <sungchun.kang@samsung.com>
Signed-off-by: Shaik Ameer Basha <shaik.ameer@samsung.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>