Revert "clocksource: arch_timer: Enable user access to the physical counter"

Disable user access to physical counter. This reverts
commit <f1a1ad6d>("clocksource: arch_timer: Enable
user access to the physical counter").

This could potentially break the userspace applications
using physical counters; but all those usages should
move to using virtual counter, to get the timing
information.

Change-Id: I653816a93515507a400ff23dbaa4442bf614a79b
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Kyle Yan <kyan@codeaurora.org>
Signed-off-by: Runmin Wang <runminw@codeaurora.org>