usb: host: xhci: change pre-increments to post-increments

This is a cleanup patch only, no functional changes. The idea is just to
make sure for loops look the same all over the driver.

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>