arm: mvebu: Add support for local interrupt

MPIC allows the use of private interrupt for each CPUs. The 28th first
interrupts are per-cpu. This patch adds support to use them.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
clocksource: time-armada-370-xp: add local timer support

On the SOCs Armada 370 and Armada XP, each CPU comes with two private
timers. This patch use the timer 0 of each CPU as local timer for the
clockevent if CONFIG_LOCAL_TIMER is selected. In the other case, use
only the private Timer 0 of CPU 0.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
arm: mvebu: update defconfig with local timer support

Now that we have support for local timers, enable it by default

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
arm: mvebu: update DT to support local timers

Now that the time-armada-370-xp support local timers, updated the
device tree to take it into account.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
clocksource: update and move armada-370-xp-timer documentation to timer directory

Timer driver for Armada 370 and Armada XP have gained local timers
support. So it needs new resources information regarding the IRQs
and the registers.

Also move the documentation in the new and more accurate directory

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>