am335x: add mux config for DDR3 version of beaglebone

This fixes the following boothang in SPL:

	Unknown board, cannot configure pinmux.### ERROR ### Please RESET the board ###

Future commits will add pinmuxes for more on-board peripherals.

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
1 file changed