msm: mdss: fb: remove unused page protection flags

In mmap implementation for mdss-fb, the argument for page protection
flags were used only in the legacy MDP drivers. Remove these
these unused flags.

Change-Id: I5d67008b5b61165d2cc87ac15e5ef544dcdf819f
Signed-off-by: Manoj Rao <manojraj@codeaurora.org>