ARM: imx: remove unneeded mach/irq.h inclusion

Remove unneeded mach/irq.h inclusion from imx platform code.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Dong Aisheng <dong.aisheng@linaro.org>