perf: arm_cspmu: Separate Arm and vendor module

Arm Coresight PMU driver consists of main standard code and
vendor backend code. Both are currently built as a single module.
This patch adds vendor registration API to separate the two to
keep things modular. The main driver requests each known backend
module during initialization and defer device binding process.
The backend module then registers an init callback to the main
driver and continue the device driver binding process.

Signed-off-by: Besar Wicaksono <bwicaksono@nvidia.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-and-tested-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Link: https://lore.kernel.org/r/20230821231608.50911-1-bwicaksono@nvidia.com


Signed-off-by: Will Deacon <will@kernel.org>