mmc: sdhci: add a quirk for tuning work around

This patch defines a quirk for tuning work
around for some sdhci host controller. It sets
both SDHCI_CTRL_EXEC_TUNING and SDHCI_CTRL_TUNED_CLK
for tuning.
It is a preparation and will be used by Fujitsu
SDHCI controller f_sdh30 driver.

Signed-off-by: Vincent Yang <Vincent.Yang@tw.fujitsu.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 3e4fe96..a3ecd20 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1961,6 +1961,8 @@
 
 	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 	ctrl |= SDHCI_CTRL_EXEC_TUNING;
+	if (host->quirks2 & SDHCI_QUIRK2_TUNING_WORK_AROUND)
+		ctrl |= SDHCI_CTRL_TUNED_CLK;
 	sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
 
 	/*