[PATCH] USB: hcd uses EXTRA_CFLAGS for -DDEBUG

This modifies the HCD builds to automatically "-DDEBUG" if
CONFIG_USB_DEBUG is selected.  It's just a minor source code cleanup,
guaranteeing consistency.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>