mmc: sdhci: fix incorrect command used in tuning

For SD hosts using retuning mode 1, when retuning timer expired, it will
need to do retuning in sdhci_request before processing the actual
request. But the retuning command is fixed: cmd19 for SD card and cmd21
for eMMC card, so we can't use the original request's command to do the
tuning.

And since the tuning command depends on the card type attached to the
host, we will need to know the card type to use the correct tuning
command.

Signed-off-by: Aaron Lu <aaron.lu@amd.com>
Reviewed-by: Philip Rakity <prakity@marvell.com>
Cc: stable <stable@vger.kernel.org> [3.3+]
Signed-off-by: Chris Ball <cjb@laptop.org>