Fix invalid M2_RST# gpio pinmux.

Fixes: ef484dfc ("arm64: dts: imx: Add i.mx8mm/imx8mn Gateworks gw7902 dts support")
Cc: stable@vger.kernel.org
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>