ARM: fix rcu stalls on SMP platforms

We can stall RCU processing on SMP platforms if a CPU sits in its idle
loop for a long time.  This happens because we don't call irq_enter()
and irq_exit() around generic_smp_call_function_interrupt() and
friends.  Add the necessary calls, and remove the one from within
ipi_timer(), so that they're all in a common place.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Change-Id: I3383645deba180958b548fbae5aca795ac4094f6
Reviewed-on: http://git-master/r/90691
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>
Reviewed-by: Scott Williams <scwilliams@nvidia.com>
Reviewed-by: Krishna Reddy <vdumpa@nvidia.com>
Reviewed-by: Juha Tukkinen <jtukkinen@nvidia.com>
Tested-by: Juha Tukkinen <jtukkinen@nvidia.com>

Conflicts:

	arch/arm/kernel/smp.c