usb: chipidea: move debug files creation/removal to the core

Create and remove debugfs entries in hdrc probe/remove instead of
start/stop of the device controller. Gadget specific will not export
anything while the controller is in host mode.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>