ARM: dts: dra7: Disable USB metastability workaround for USB2

The metastability workaround causes Erratic errors [1]
on the HighSpeed USB PHY which can cause upto 2 seconds
delay in enumerating to a USB host while in Gadget mode.

Disable the Run/Stop metastability workaround to avoid this
ill effect. We are aware that this opens up the opportunity
for Run/Stop metastability, however this issue has never been
observed in TI releases so we think that Run/Stop metastability
is a lesser evil than the PHY Erratic errors. So disable it.

[1] USB controller trace during gadget enumeration
    irq/90-dwc3-969   [000] d...    52.323145: dwc3_event: event
    (00000901): Erratic Error [U0]
    irq/90-dwc3-969   [000] d...    52.560646: dwc3_event: event
    (00000901): Erratic Error [U0]
    irq/90-dwc3-969   [000] d...    52.798144: dwc3_event: event
    (00000901): Erratic Error [U0]

Signed-off-by: Roger Quadros <rogerq@ti.com>
Acked-by: Felipe Balbi <felipe.balbi@linux/intel.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>