usb: dwc2: Add eUSB2 PHY disconnect flow support

To support eUSB2 PHY disconnect flow required in Soft disconnect
state set GOTGCTL_EUSB2_DISC_SUPP bit, if applicable.

On Session End Detected interrupt clear PCGCTL_GATEHCLK and
PCGCTL_STOPPCLK bits if eusb2_disc parameter true.

Signed-off-by: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Link: https://lore.kernel.org/r/9d50b83df693cda8c391313e90048df8dd611c04.1708948356.git.Minas.Harutyunyan@synopsys.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>