usb: host: xhci: convert several if() to a single switch statement

when getting endpoint type, a switch statement looks
better than a series of if () branches. There are no
functional changes with this patch, cleanup only.

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>