mmc: sdhci-msm: Clear tuning done flag while hs400 tuning

Clear tuning_done flag while executing tuning to ensure vendor
specific HS400 settings are applied properly when the controller
is re-initialized in HS400 mode.

Without this, re-initialization of the qcom SDHC in HS400 mode fails
while resuming the driver from runtime-suspend or system-suspend.

Fixes: ff06ce4 ("mmc: sdhci-msm: Add HS400 platform support")
Cc: stable@vger.kernel.org
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
Link: https://lore.kernel.org/r/1590678838-18099-1-git-send-email-vbadigan@codeaurora.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-msm.c

@@ -1173,6 +1173,12 @@ static int sdhci_msm_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	/* Clock-Data-Recovery used to dynamically adjust RX sampling point */
 	msm_host->use_cdr = true;
 
+	/*
+	 * Clear tuning_done flag before tuning to ensure proper
+	 * HS400 settings.
+	 */
+	msm_host->tuning_done = 0;
+
 	/*
 	 * For HS400 tuning in HS200 timing requires:
 	 * - select MCLK/2 in VENDOR_SPEC