msm_fb: display: force mdp clock off at suspend

At suspend, turn off mdp related clocks off if clocks
are not turned off by vsync disable request.

Change-Id: I0949b00b9ee0aee05b9b553ac7318b647052d94d
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
(cherry picked from commit 780557dc178fc5511f4c03b4840791d27499a5f6)