arm64: dts: librem5: Use edge triggered irq for touch

The touch controller supports two modes but default seemds to be
edge.

Closes: #136

and helps #125 and #133.

Signed-off-by: Guido Günther <guido.gunther@puri.sm>
2 jobs for mrs/touch-irq in 41 minutes and 22 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #240725
librem5
build:aarch64

00:11:54

passed #240726
librem5:arm64
build:deb

00:41:21