From: James Morse <james.morse@arm.com>

MPAM's MSC support a number of monitors, each of which supports
bandwidth counters, or cache-storage-utilisation counters. To use a counter, a
monitor needs to be configured. Add helpers to allocate and free CSU or MBWU
monitors.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Tested-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Shaopeng Tan <redacted>
Tested-by: Peter Newman <redacted>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>

Reviewed-by: Shaopeng Tan <redacted>