Disables PING on status phase of control transfer.
PING token is not mandatory in status phase of control transfer
and so some high speed USB devices don't support it. If such devices
are connected to MUSB then they would not respond to PING token
causing delayed or failed enumeration.

[Roger Q] Fixes enumeration issues with some Super-Speed USB hubs
e.g. Dlink DUB-1340
Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>