usb: Use the USB_SS_MULT() macro to decode burst multiplier for log message

usb_parse_ss_endpoint_companion() now decodes the burst multiplier
correctly in order to check that it's <= 3, but still uses the wrong
expression if warning that it's > 3.

Fixes: ff30cbc8

 ("usb: Use the USB_SS_MULT() macro to get the ...")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>