mmc: make mmc_send_status() more reliable

Align the card status polling with the Linux kernel and retry the
command at least five times. Also some cards apparently mishandle the
status bits, so make sure to check the card state too.

Signed-off-by: Jan Kloetzke <jan.kloetzke@dspg.com>
Cc: Andy Fleming <afleming@gmail.com>