irqchip/mxs: Panic if ioremap or domain creation fails

Current code will only warn and then dereference the NULL pointer or
continue, which results in a fatal NULL pointer dereference later.

If the initialization fails, the machine is unusable, so panic right
away.

[ tglx: Massaged changelog and picked the irqdomain panic from the
  	next patch]

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/1444677334-12242-2-git-send-email-linux@rempel-privat.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>