arm64: dts: librem5-devkit: Move headphone detection to sound card

This allows for automatic output source switching in userspace. Enable
the pullup on the GPIO to actually make it trigger and mark it as
active-high since detection is reversed otherwise.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>