ARM: perf: consolidate common PMU behaviour

The functions for mapping PMU events (perf, cache and raw) are
common between all PMU types and differ only in the data on which
they operate.

This patch implements common definitions of these mapping functions
and changes the arm_pmu struct to hold pointers to the data which
they require. This is in anticipation of separating out the PMU-specific
code into separate files.

Acked-by: Jamie Iles <jamie.iles@jamieiles.com>
Acked-by: Jean Pihet <j-pihet@ti.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>