msm: mdss: Increase fbmem ref count before use

(cherry-pick from 'commit a1b61bc4 ("msm: mdss: Increase
 fbmem buf ref count before use")') and made similar
changes for MDP3.

The reference count for fbmem buf is not incremented
before use, which means it can get freed unintentionally
when the ref countis decreased to "0". In this case,
there is a possibility of use after free. Ensure the
fbmem buf refcount is incremented before use.

Change-Id: Iab89ac332dd447b29514a6d5c3f251fcd145de4d
Signed-off-by: Nirmal Abraham <nabrah@codeaurora.org>