Currently if we bootup a device without cable connected, then
usb-conn-gpio won't call set_role() since last_role is same as
current role. This happens because during probe last_role gets
initialised to zero.
To avoid this, added a new constant in enum usb_role, last_role
is set to USB_ROLE_UNKNOWN before performing initial detection.
While at it, also handle default case for the usb_role switch
in cdns3 to avoid build warnings.
Fixes: 4602f3bff266 ("usb: common: add USB GPIO based connection detection driver")
Signed-off-by: Prashanth K <quic_prashk@xxxxxxxxxxx>