hyperv: Remove unused union and structs

The union vmpacket_largest_possible_header and several structs have not
been used for a long time afaict - remove them.

Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://lore.kernel.org/r/20250311091634.494888-2-thorsten.blum@linux.dev


Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250311091634.494888-2-thorsten.blum@linux.dev>