usb: musb: am335x-evm: Do not remove the session bit HOST-only mode

This is what I observe:
On the first connect, the musb starts with DEVCTL.Session set. On
disconnect, musb_core calls try_idle. That functions removes the Session
bit signalizing that the session is over (something that only in OTG is
required). A new device, that is plugged, is no longer recognized.
I've setup a timer and checked the DEVCTL register and I haven't seen a
change in VBus and I saw the B-Device bit set. After setting the IDDIG
into A mode and forcing the device to behave like a A device, I didn't
see a change.
Neither VBUS goes to 0b11 nor does a session start request comes.
In the TI-v3.2 kernel they skip to call musb_platform_try_idle() in the
OTG_STATE_A_WAIT_BCON state while not in OTG mode.
Since the second port hast a standard A plug the patch changes the port
to run in host mode only and skips the timer which would remove
DEVCTL.Session so we can reconnect to another device later.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>