MIPS: ralink: Fix mt7620 nd_sd pinmux

In case the nd_sd group is set to the sd-card function, Pins 45 + 46 are
configured as GPIOs. If they are blocked by the sd function, they can't
be used as GPIOs.

Reported-by: Kristian Evensen <kristian.evensen@gmail.com>
Signed-off-by: Mathias Kresin <dev@kresin.me>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: f576fb6a ("MIPS: ralink: cleanup the soc specific pinmux data")
Patchwork: https://patchwork.linux-mips.org/patch/21220/
Cc: John Crispin <john@phrozen.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org # v3.18+