Adds a new driver to support the SMMUv3 PMU and add it into the
perf events framework.

Each SMMU node may have multiple PMUs associated with it, each of
which may support different events.

SMMUv3 PMCG devices are named as smmuv3_pmcg_<phys_addr_page> where
<phys_addr_page> is the physical page address of the SMMU PMCG
wrapped to 4K boundary. For example, the PMCG at 0xff88840000 is
named smmuv3_pmcg_ff88840

Filtering by stream id is done by specifying filtering parameters
with the event. options are:
   filter_enable    - 0 = no filtering, 1 = filtering enabled
   filter_span      - 0 = exact match, 1 = pattern match
   filter_stream_id - pattern to filter against

Example: perf stat -e smmuv3_pmcg_ff88840/transaction,filter_enable=1,
                       filter_span=1,filter_stream_id=0x42/ -a netperf

Applies filter pattern 0x42 to transaction events, which means events
matching stream ids 0x42 & 0x43 are counted as only upper StreamID
bits are required to match the given filter. Further filtering
information is available in the SMMU documentation.

SMMU events are not attributable to a CPU, so task mode and sampling
are not supported.
Signed-off-by: Neil Leeder <nleeder@codeaurora.org>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
[will: fold in review feedback from Robin]
[will: rewrite Kconfig text and allow building as a module]
Signed-off-by: Will Deacon <will.deacon@arm.com>