usb: xhci: Make some static functions global

usb: xhci: Make some static functions global

BugLink: http://bugs.launchpad.net/bugs/1730832
This patch makes some static functions global to avoid duplications
in different files. These functions can be used in the implementation
of xHCI debug capability. There is no functional change.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 67d2ea9fde2aa96f36af0537e4004efb123319fb)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>