mdss: Fix null point dereference in mdss_mdp_pp_init

Fixed null point dereference in case of memory allocation
failure in mdss_mdp_pp_init.

Change-Id: I3593a583da355915b731ac30b1f38aaa010eba85
Signed-off-by: Krishna Chaitanya Parimi<cparimi@codeaurora.org>
make it compile with CONFIG_SEC_DEBUG enabled