ixgbevf: Remove unused ixgbevf_hv_mbx_ops

The const struct ixgbevf_hv_mbx_ops was added in 2016 as part of
commit c6d45171 ("ixgbevf: Support Windows hosts (Hyper-V)")

but has remained unused.

The functions it references are still referenced elsewhere.

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://patch.msgid.link/20250105122847.27341-1-linux@treblig.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>