usb-storage: remove UNUSUAL_VENDOR_INTF macro

This patch removes macro that was used only by commit that was reverted
in commit ab4b7164 ("USB: storage: fix Huawei mode switching
regression")

Signed-off-by: Milan Broz <gmazyland@gmail.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20231016072604.40179-2-gmazyland@gmail.com


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