ARM: perf: allow armpmu to implement mode exclusion
Modern PMUs allow for mode exclusion, so we no longer wish to return
-EPERM if it is requested.
This patch provides a hook in the armpmu structure for implementing
mode exclusion. The hw_perf_event initialisation is slightly delayed so
that the backend code can update the structure if required.
Acked-by: Jamie Iles <jamie@jamieiles.com> Reviewed-by: Jean Pihet <j-pihet@ti.com> Signed-off-by: Will Deacon <will.deacon@arm.com>