i915/perf: Drop the check for report reason in OA

After fixing the OA_TAIL_PTR corruption, there are no more reports with
reason field of zero. Drop the check for report reason.

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210210190106.8586-1-umesh.nerlige.ramappa@intel.com