Use MEMZERO() instead of its pattern

Use MEMZERO() instead of its pattern

This patch implicitly adds the safety of SIZEOF_ARRAY(), since the calls
were using sizeof() instead.

Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>