irqchip/mxs: Add Alphascale ASM9260 support

Freescale iMX23/iMX28 and Alphascale ASM9260 have similar interrupt
collectors. We already prepared the mxs driver to handle a different
register layout. Add the actual ASM9260 support.

Differences between these devices:
- Different register offsets
- Different count of interupt lines per register
- ASM9260 does not provide reset bit
- ASM9260 does not support FIQ.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Tested-by: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: marc.zyngier@arm.com
Cc: jason@lakedaemon.net
Link: http://lkml.kernel.org/r/1444677334-12242-6-git-send-email-linux@rempel-privat.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>