mmc: sdhci: Separate timer timeout for command and data requests

In order to support commands during data transfer, there will have to be up
to two active requests (mrqs) at a time, instead of just one. Provide two
timers instead of just one. One of the timers is for requests that do not
use the data lines, and the other one is for requests that do.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>