ANDROID: mpam_arch: Add CMAX MSC feature support

This serves as nicely segmented example as to what it takes to add support
for a given partitioning feature.

Note that CMAX is supposed to be a fixed point fraction but the exposed
interface is just the "raw" value.

Change-Id: I8274dcd7f2ba8941f4e9b1d6376bf0a4e89ad831
Signed-off-by: Valentin Schneider <Valentin.Schneider@arm.com>