usb: chipidea: use common definition for USBMODE bits

Some of the bits of USBMODE register are defined in <usb/ehci_def.h>,
use them instead of having our own definitions.

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