Convert the "R1B fix" from a busy-loop in the interrupt handler to a callout.
Increase the wait time for acquiring the bus from 10 to 250ms.

Normally it never needs to wait here at all; waiting is done at the end
of the prior command.  When doing a crash dump, the normal interrupt
mechanism isn't used; instead the interrupt handler is called repeatedly
in a polling-like manner.  This can subvert hardware-specific drivers
and lead to trying to start a new command while the previous command is
still busy on the bus.  Since the SD spec says the longest a card can
take to execute any command is 250ms, use that as a timeout.