mfi(4): Stop checking for failures from malloc(M_WAITOK)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D45852
(cherry picked from commit 701308ef404f552034f8c3e3e912b41bfef28ee6)
(cherry picked from commit 4fee8d3e92c69d5865a7ef1a9102399b6fdeb9bc)