ANDROID: db845c_gki.fragment: Remove CONFIG_USB_NET_AX88*

Commit 55adb91a ("ANDROID: GKI: enable some USB_NET_ config
options") implicitly enabled the CONFIG_USB_NET_AX88* options
which was causing trouble with the db845C_gki.fragment, since
we try to load these (along with PHYLIB) as modules.

So drop these, and it should work out.

Fixes: 55adb91a ("ANDROID: GKI: enable some USB_NET_ config options")
Signed-off-by: John Stultz <john.stultz@linaro.org>
Change-Id: Ia7e69d7030842f5136aafc064e1ba8a70bad2bb6