disp: msm: sde: reserve dscs considering hw pairs

RM does not currently check dsc pairs while reserving, but
this could lead to an incompatible pair being allocated. The
hw restrictions are populated from dtsi and checked during
rm reservation.

Change-Id: If561e2bd64c7643ed9ee71a255242eab84576673
Signed-off-by: Nilaan Gunabalachandran <ngunabal@codeaurora.org>