msm: mdss: Fix single pipe AD tile control

The tile control parameter is used by the Assertive Display
block to control merged mode or independent mode AD for
dual-pipe AD. However, in single pipe AD, the tile control
should always be set to zero.

Change-Id: I0dd3c3b716fd5156d9a0f9206911159d186fd9c7
Signed-off-by: Benet Clark <benetc@codeaurora.org>