usb: otg: mxs-phy: Fix mx23 operation

usb: otg: mxs-phy: Fix mx23 operation

commit 363366cf61c544ea476f3d220f43a95cb03014f5 upstream.

Currently mx23 fails to enumerate a USB device:

[ 1.300000] hub 1-0:1.0: unable to enumerate USB device on port 1
[ 1.520000] hub 1-0:1.0: unable to enumerate USB device on port 1
[ 1.740000] hub 1-0:1.0: unable to enumerate USB device on port 1
[ 1.960000] hub 1-0:1.0: unable to enumerate USB device on port 1
[ 2.180000] hub 1-0:1.0: unable to enumerate USB device on port 1

Use a kernel workqueue to asynchronously delay the setting of
ENHOSTDISCONDETECT bit until after higher level hub connect/reset processing
is complete.  Prematurely setting the bit prevents the connection
processing from completing and not setting it prevents disconnect from being
detected. No delay is needed for clearing of ENHOSTDISCONDETECT.

Successfully tested on mx23-olinuxino (micro, mini and maxi variants) and mx28evk.

Signed-off-by: Mike Thompson <mpthompson@gmail.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>