ARM: dts: Fix boot regression on Skomer

The signal routing on the Skomer board was incorrect making
it impossible to mount root from the SD card. Fix this up.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: stable@vger.kernel.org
Cc: Stefan Hansson <newbyte@disroot.org>
Link: https://lore.kernel.org/r/20220205235312.446730-1-linus.walleij@linaro.org'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>