clocksource: arch_timer: Do not register arch_sys_counter twice

Commit:

   65cd4f6c ("arch_timer: Move to generic sched_clock framework")

added code to register the arch_sys_counter in arch_timer_register(),
but it is already registered in arch_counter_register().

This results in the timer being added to the clocksource list twice,
therefore causing an infinite loop in the list.

Remove the duplicate registration and register the scheduler
clock after the original registration instead.

This fixes a hang during boot on Tegra114 (Cortex-A15).

[ While I've only tested this on Tegra114, I suspect the same hang
  during boot happens for all processors that use this clock source. ]

Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: http://lkml.kernel.org/r/1381843911-31962-1-git-send-email-treding@nvidia.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>