MLK-11269-2 usb: chipidea: host: avoid check PORT_SUSPEND wrongly

At some situations, the ehci_bus_suspend may not set PORT_SUSPEND
due to port is not enabled, so add flag ehci->bus_suspended to
check if ehci_bus_suspend set PORT_SUSPEND or not.

We see "ci_hdrc ci_hdrc.0: timeout waiting for SUSPEND" wrongly when
plug in an unsupported usb device, in that case, the PORT_PE is cleared
and bus_suspend is called.

Signed-off-by: Peter Chen <peter.chen@freescale.com>
(cherry picked from commit 82cfe6c31ee55e5aab1a057a5aaf853b7bb6cd07)