ARM: imx27: Use 'AITC' for the interrupt controller name

On the MX27 Reference Manual the interrupt controller is named AITC:
ARM926EJ-S Interrupt Controller

So use the AITC term instead of AVIC.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Origin: id:1334193132-18944-2-git-send-email-festevam@gmail.com
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>