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.

Reserve DSC in the sequence of primary and peer, and then
primary-peer again until all required DSC are reserved.

The logic can also work for any number of DSC reservetion
and make sure that all the reserved DSCs are in pairs except
the last one if total DSC number is odd, including single DSC
case.

Change-Id: Ie7ffa7a0fba3c2d076fe7db4cff052e765825ebf
Signed-off-by: Jim Wang <jimwan@codeaurora.org>