ARM: local timers: introduce a new registration interface

In order to switch to a runtime selectable local timer,
add a registration interface that timer drivers can use to
register to the core.

local_timer_setup() and local_timer_stop() are made weak symbols
in order not to break existing setups.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
ARM: twd: fix display of twd frequency

The fraction of MHz was not being displayed correctly as the calculation
was a factor of 10 out.  Fix this.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Conflicts:
	arch/arm/kernel/smp_twd.c
ARM: local timers: Add A15 architected timer support-MSM

Add support for the A15 generic timer and clocksource.
As the timer generates interrupts on a different PPI depending
on the execution mode (normal or secure), it is possible to
register two different PPIs.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Conflicts:
        [Integrate to the recent patch which has changes to
         local timer registration mechanism.

         This fixes the crash seen during hotplug operations
         where after a secondary CPU is brought back online,
         the clock event device setup was happening as part
         of the online notification mechanism which was too
         late. With this change in the local timer mechanims,
         the clock event device is now setup as part of the
         secondary CPU boot initialization making it available
         early enough for use.

         Update the board file with the appropriate changes in
         the argument for timer registration.]
	arch/arm/Kconfig
	arch/arm/include/asm/arch_timer.h
	arch/arm/kernel/arch_timer.c
	arch/arm/kernel/smp.c

Change-Id: I0bc80097c145fb2aac2150db0c5dff3c5e215a58
Signed-off-by: Sathish Ambley <sambley@codeaurora.org>
(cherry picked from commit df590ccd9d8210cc3e059671efad06dab7e70d4c)

Change-Id: Iedac55e097b8d983c42799b98f2d11f7b1a95f04
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>

Conflicts:
	arch/arm/kernel/smp.c
Revert this
Revert "Revert this"

This reverts commit 71d5548579d5f26c3f78e8c793384cd64dfd92ee.