arm64: dts: apple: touchbar: Mark ps_dispdfr_be as always-on

The driver depends on boot loader initialized state which resets when the
ps_dispdfr_be power-domain is powered off. This happens on suspend or
when the driver is missing during boot.
Mark the domain as always on until the driver can handle this.

Fixes: 7275e795 ("arm64: dts: apple: Add touchbar screen nodes")
Signed-off-by: Janne Grunau <j@jannau.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Link: https://lore.kernel.org/r/20250416-arm64_dts_apple_touchbar-v1-1-e1c0b53b9125@jannau.net


Signed-off-by: Sven Peter <sven@svenpeter.dev>