.. which is what the addition of cmd25 made happen. We still signal
an error when failing to reach the idle state at any other time,
which _is_ different than adafruit_sdcard but I think that it is
correct.
This fixed#5600 according to Dan's testing on a GCM4 on the internal
SD card slot. There are still some ambiguous results on the MM4 with
external SD card slot on 6" jumper wires.
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