linux-wandboard

MLK-10994-4 usb: ehci: Keep portsc unchanging when power off port

If PORT_RWC_BITS is set, it will still be cleared by writing 1.
portsc.ptw can only be changed when PHY clock is off and portsc.phcd is set,
if not, the PHY will be error, so we keep portsc.ptw unchanging
in this patch.

Signed-off-by: Peter Chen <peter.chen@freescale.com>
(cherry picked from commit 24c2f76ab5b1c1d2b4bc26f95ed68e44f6768b8b)