net: usb: sr9700: remove code to drive nonexistent multicast filter

net: usb: sr9700: remove code to drive nonexistent multicast filter

Several registers referenced in this driver's source code do not
actually exist (they are not writable and read as zero in my testing).
They exist in this driver because it originated as a copy of the dm9601
driver. Notably, these include the multicast filter registers - this
causes the driver to not support multicast packets correctly. Remove
the multicast filter code and register definitions. Instead, set the
chip to receive all multicast filter packets when any multicast
addresses are in the list.

Reviewed-by: Simon Horman <horms@kernel.org> (from v1)
Signed-off-by: Ethan Nelson-Moore <enelsonmoore@gmail.com>
Link: https://patch.msgid.link/20260203013924.28582-1-enelsonmoore@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>