net: usb: int51x1: use usbnet_cdc_update_filter

net: usb: int51x1: use usbnet_cdc_update_filter

The int51x1 driver uses the same requests as USB CDC to handle packet
filtering, but provides its own definitions and function to handle it.
The chip datasheet says the requests are CDC compliant. Replace this
unnecessary code with a reference to usbnet_cdc_update_filter.

Also fix the broken datasheet link and remove an empty comment.

Signed-off-by: Ethan Nelson-Moore <enelsonmoore@gmail.com>
Link: https://patch.msgid.link/20260126044049.40359-1-enelsonmoore@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>