msm: mdss: fix screen shifting in some scenarios when split display enabled

Split display configuration requires that lower and upper pipe
control registers get programmed accordingly. This change fixes
a missing configuration bit in one of the control registers.

Change-Id: I17c71c004dbf6807483f132cb22271230b27960c
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>