gui: introduce screen and surface to factorize and simplify code
Instead of passing hundreds of parameter, just pass the right structure.
struct screen represent the screen with a without double buffering.
struct surface represent the part of the screen we want to render.
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>