Fix hang at init for MagicMedia 256A[VX] chips. [1]
In case this causes trouble for some other chipsets add a comment how to
proceed. If we don't get bugreports, this should be removed after a while
(some releases?).
PR: 56617 [1], 29465, 39260, 40574, 68225
Submitted by: Matthew E. Gove <mgove@comcast.net> [1]