mach-ux500: DB8500 PMU support

DB8500 has irqs from two cores ORed into one. Implement a
workaround to handle this by bouncing the interrupt by setting
the affinity to the other core when the interrupt appears to
be spurious on the current core.

Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>