libgscaler: rework configuration checking and alignment

Rewritten based on constraints listed in Gscaler application note,
extracted to its own file for readability, and exposed to other modules
(i.e. the HWC) through exynos_gscaler.h.

Change-Id: I963596bbee6301fdf55f6956a0bf6b44de42c861
Signed-off-by: Greg Hackmann <ghackmann@google.com>
4 files changed