Revert "usb: roles: don't get/set_role() when usb_role_switch is unregistered"

This reverts commit eb369345 which is
commit b787a3e7 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.  It's not a "real" break, and
we can work around it, but this really does not affect Android systems,
so it's safe to drop for now.

Bug: 161946584
Change-Id: I82f2a6b9ecb9ebaef30df164859305605f477f24
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>