perf: Skip permission checks on kernel owned perf events

The perf event permission checks are necessary because they introduce
a security concern where one userspace task can monitor another task
and gain security related information. That concern doesn't exist for
kernel owned perf events since the kernel already has access to
everything. So, skip permission checks for kernel owned perf events.

Change-Id: I7121f5e03cf6ce8f0bfc9b5a69488efb80a97051
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>