sdhci(4): Stop checking for failures from malloc(M_WAITOK)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D45852
(cherry picked from commit f80483cdd58a032ae2cfb2b9119824e9badc2c91)
(cherry picked from commit 5a7db2ff56f9e08579913ae16850ff82617001dc)