msm_fb: display: decrease file->f_count when play

Frame buffer's (fb0) f_count needed to be decreased after both
overlay play and rotation so that fb0 can be closed and display
will be blanked out after system suspended.

CRs-fixed: 336254
Change-Id: I966e7b2bb4def0c9c09580be12048933723e2c2e
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>