MIPS: ralink: MT7688 pinmux fixes

A few fixes to the pinmux data, 2 new muxes and a minor whitespace
cleanup.

Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11991/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>