ANDROID: USB: gadget: removed unused android device functions.

In commit 957b40b3 ("ANDROID: usb: gadget: configfs: Add Uevent to
notify userspace"), the functions android_create_function_device() and
android_remove_function_device() were added and exported, but no device
actually ever calls these as they are not exported in the Android device
symbol lists.

Remove these as they are not being used by anyone.  They can come back
in the future if ever needed.

Bug: 120441124
Bug: 317149848
Bug: 352124133
Fixes: 957b40b3 ("ANDROID: usb: gadget: configfs: Add Uevent to notify userspace")
Cc: Neill Kapron <nkapron@google.com>
Cc: Elson Roy Serrao <quic_eserrao@quicinc.com>
Change-Id: I032ec78e18d60944a4e32c9b835001dfbc46bd1d
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>