[media] gscaler: Add m2m functionality for the G-Scaler driver

This patch adds the memory to memory (m2m) interface functionality
for the G-Scaler driver.

[mchehab@redhat.com: Fixed a small coding style issue:
 sizeof *ctx should be sizeof(*ctx)]
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>