commit 28c56ea1 upstream.

If USB UTMI PHY is not enable, writing to portsc register will lead to
kernel hang during boot up.
Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>