In current design, the user of perf app needs to input counter ID to count
events. However, this is not user-friendly since the user needs to lookup
the map table to find the counter. Instead of letting the user to input
the counter, let this driver to manage the counters in this patch.

This will be implemented by:
 1. allocate counter 0 for cycle event.
 2. find unused counter from 1-10 for reference events.
 3. allocate specific counter for counter-specific events.

In this patch, counter attr will be kept for back-compatible but all the
value passed down by counter=<n> will be ignored. To mark counter-specific
events, counter ID will be encoded into perf_pmu_events_attr.id.
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Link: https://lore.kernel.org/r/20240529080358.703784-3-xu.yang_2@nxp.comSigned-off-by: Will Deacon <will@kernel.org>