USB: ehci_omap: fix device detect issue with modules

Currently devices don't get detected automatically if the ehci
module is inserted 2nd time onward. We need to disconnect and
reconnect the device for it to get detected and enumerated.

Resetting the USB PHY using PHY reset comamnd over ULPI fixes
this issue. Tested on OMAP3EVM.

Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Acked-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>