ARM: imx: merge audmux-v1 and audmux-v2

It merges audmux-v1 and audmux-v2 under arch/arm/plat-mxc into one.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>