amr64: dts: librem5: disable auto DPDM

The bq25892 shares the USB 2 DP/DM with the dwc3 disable the auto negotiation
so there is no contention.

Signed-off-by: Angus Ainslie <angus@akkea.ca>
2 jobs for auto-dpdm in 71 minutes and 54 seconds (queued for 1 second)
Status Name Job ID Coverage
  Build
passed build:aarch64 #304726
librem5

00:17:47

passed build:deb #304727
librem5:arm64

01:11:54