ANDROID: db845c_gki.fragment: Drop CONFIG_USB_DWC3 from config frament

As of commit 42d1d3ff ("ANDROID: GKI: enable CONFIG_USB_DWC3
to be build in"), we no longer need CONFIG_USB_DWC3=m in the
db845c_gki.frament, as having it there, causing the module load
to fail (as its duplicative) and the boot to (unfortunately
silently) fail.

Fixes: 42d1d3ff ("ANDROID: GKI: enable CONFIG_USB_DWC3 to be build in")
Change-Id: I089b91364868ef56ac3da158f62c0c5f5345a1a4
Signed-off-by: John Stultz <john.stultz@linaro.org>