mmc: sdhci: Program a relatively accurate SW timeout value

sdhci has a 10 second timeout to catch devices that stop responding.
In the case of quirk SDHCI_QUIRK2_DISABLE_HW_TIMEOUT, instead of
programming 10 second arbitrary value, calculate the total time it would
take for the entire transfer to happen and program the timeout value
accordingly.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>