usb: dwc3: make macros safe to expression arguments

We must make sure that our macros are safe against expressions passed
as arguments. We have seen one problem where GTXFIFOSIZ(n) was failing
when passed the expression (epnum >> 1) as argument. The problem was
caused by operator precedence between >> and *.

To make sure macros are safe, we just wrap argument with () when using
it.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>