Linux 5.15 does not have the linux/ipx.h header.

The patch is a partial cherry-pick (skipped ChangeLog) of upstream
commit 6b09724c6 ("Make IPX packet interpretation dependent on the ipx
header file existing").

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
(cherry picked from commit 7be14da0d59ef59bfcb4b8c38fa9c93038cde8fb)