mlx(4): Stop checking for failures from malloc(M_WAITOK)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D45852
(cherry picked from commit 556cd18fb07604e3442819b221afb2a19b924dbd)
(cherry picked from commit cf44738feb83b03f0726ae1dab83daf371aa2f0a)