i.MX31: Fix mx31_gpio_mux() function and MUX_-macros.

Correct the mx31_gpio_mux() function to allow changing all i.MX31 IOMUX
contacts instead of only the first 256 ones as is the case prior to
this patch.

Add missing MUX_* macros and update board files to use the new macros.

Signed-off-by: Magnus Lilja <lilja.magnus@gmail.com>
4 files changed