uboot-imx

imx6: tqma6: disable spi CS unused in U-Boot

Since the CS are not in use, do not map them. User of starterkit
mainboard is free to use them otherwise. When using these pins later
in the OS for instance as GPIO IRQ pin, they need to be input.

Signed-off-by: Markus Niebel <Markus.Niebel@tq-group.com>