drm/msm/sde: fix atomic check for crtc driver

Current crtc module checks the number of planes
against the number of z order supported. This is not
a valid check because hardware may support less
z order stages compared to number of planes. This patch
fixes those checks and adds additional bound check
like plane is within crtc boundary, two planes do not
request for same z order, etc during atomic check.

Change-Id: If571888ec02f8aa94972543c76e8c5895751089a
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>