ARM: ux500: fix MMC/SD card regression

Ux500 is regressing due to commit
a21763a0
"pinctrl: nomadik: activate strict mux mode" which disallows
Nomadik GPIO 5 to be muxed in as a level shifter voltage select
pin, as it is currently described as being used for RX on UART1.

The behaviour is correct, instead the hardware config has been
incorrecly specified: UART1 is indeed unused on HREFv60plus and
Snowball and that is why HREFv60plus can use the pins it would
normally occupy as the voltage select line for the MMC/SD
levelshifter (Snowball uses it for I2C4).

The reason UART1 was anyway enabled on these platforms was
probably to secure the port enumeration to userspace. This
can be solved by using aliases (done in a separate patch) so
we can now deactivate UART1 and let MMC/SD use it properly
on HREFv60plus. We explicitly activate it only for the
older HREFprev60 board.

To complete, we set up the pin configuration for these pins
properly in the sdi0 node.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>