mmc: Handle wbsd's stupid command list

The wbsd hardware is so incredibly brain damaged that it has an internal
list of commands that result in data transfers. The result being that
commands that aren't on this list aren't supported.

Instead of locking up, waiting for a data interrupt that will never come,
we try to fail a bit more gracefully.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>