usb: typec: tps6598x: Add debugfs entries for customer use word

This allows to verify that a sane firmware is on the device.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
2 jobs for usb-c-current in 74 minutes and 5 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #320417
librem5
build:aarch64

00:41:54

passed #320418
librem5:arm64
build:deb

01:14:05