91199f4a5a broke mmc based Falcon mode.
The block_read function returns the number of blocks read thus the error
check needs to look for a return of 0 blocks read.
Cc: Paul Kocialkowski <contact@paulk.fr>
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Acked-by: Paul Kocialkowski <contact@paulk.fr>