perf/arm-cmn: Stop claiming all the resources

Carl reports that when both the MPAM driver and CMN driver are built
into the kernel, they fight over who can claim the resources associated
with their registers. This prevents the second of these two drivers
from probing.

Currently the CMN PMU driver claims all the CMN registers.

The MPAM registers are grouped together in a small number of pages,
whereas the PMU registers that the CMN PMU driver uses appear
throughout the CMN register space.

Having the CMN driver claim all the resources is the wrong thing
to do, and claiming individual registers here and there is not
worthwhile.
Instead, stop the CMN driver from claiming any resources as its
registers are not grouped together.

Reported-by: Carl Worth <carl@os.amperecomputing.com>
Signed-off-by: James Morse <james.morse@arm.com>