usb: chipidea: Fix Internal error: : 808 [#1] ARM related to STS flag

* init the sts flag to 0 (missed)
* fix write the real bit not sts value
* Set PORTCS_STS and DEVLC_STS only if sts = 1

[Peter Chen: This one and the next patch fix the problem occurred imx27
and imx31, and imx27 and imx31 usb support are enabled until 3.14, so
these two patches isn't needed for -stable]

Signed-off-by: Chris Ruehl <chris.ruehl@gtsys.com.hk>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>