board: ti: dra71: Add pinmux settings for NAND on DRA71x EVM

board: ti: dra71: Add pinmux settings for NAND on DRA71x EVM

By default VOUT3 occupies the pins required for NAND. Therefore, create
a seperate entry that can be use to reconfigure these pins to work for
NAND.

On the EVM SWITCH 8 pins 0 and 1 will be used to determine if NAND is
enabled or not. For NAND to be selected pin 0 should be on and pin 1
should be off. Any other combination will assume NAND shouldn't be
enabled.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>