usb: dwc2: drd: add role-switch-default-node support

When using usb-role-switch, while the usb role is not yet define
(USB_ROLE_NONE), the user may want to configure the default mode to host
or device.
Use role-switch-default-mode for that purpose.

Acked-by: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/1638806203-6624-3-git-send-email-fabrice.gasnier@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>