staging: r8188eu: interface type is always usb

SupportInterface in struct odm_dm_struct is always ODM_ITRF_USB.
Remove the variable and the code to configure the interface.

Acked-by: Michael Straube <straube.linux@gmail.com>
Acked-by: Phillip Potter <phil@philpotter.co.uk>
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211016113008.27549-3-martin@kaiser.cx


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