ARM: dts: dra7: workaround silicon limitation i845

Silicon limitation i845 documents how to cope with false
disconnection condition on USB2 PHY. Reference: AM572x
silicon errata document SPRZ429H, revised January 2016.

Using compatible "ti,dra7x-usb2" enables the recommended
software workaround for this issue. Use it for USB1 PHY.

The workaround is already in place for USB2 PHY.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>