msm: mdss: Fix atomic commit compat layer copy

The compat layer for atomic commit is incorrectly using compat
pointers. This change adds correct support for copying all
nested compat pointers in the atomic commit structure. It also
returns the correct error value when copy_from_user fails.

Change-Id: If35a00583cfed105a16ffa547813c386314bff9b
Signed-off-by: Benet Clark <benetc@codeaurora.org>