drm/msm/a6xx: Remove CP perfcounter selects from the protected list

The CP performance counter selects were accidentally marked as protected
so they couldn't be written from PM4 streams. Remove the protection
because user space does have an interest in setting up their own
counters.

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>