linux/libusb: do not check bDeviceClass on enumeration

Some composite devices do not have bDeviceClass set to
LIBUSB_CLASS_PER_INTERFACE and were ignored when enumerating HID devices.

Ignore checking the bDeviceClass as we will be checking interface
bInterfaceClass later anyway.

Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>