Revert "mmc: sdhci: Disable SD card clock before changing parameters"

It has turned out the trying to strictly conform to the SDHCI specification
is causing problems. Let's revert and start over.

This reverts commit fb3bbc4.

Cc: Erick Shepherd <erick.shepherd@ni.com>
Cc: stable@vger.kernel.org
Fixes: fb3bbc4 ("mmc: sdhci: Disable SD card clock before changing parameters")
Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
Reported-by: Jonathan Liu <net147@gmail.com>
Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Closes: https://bugs.debian.org/1108065
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20250624110932.176925-1-ulf.hansson@linaro.org

Author: Ulf Hansson

drivers/mmc/host/sdhci.c

@@ -2065,15 +2065,10 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
 
 	host->mmc->actual_clock = 0;
 
-	clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
-	if (clk & SDHCI_CLOCK_CARD_EN)
-		sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN,
-			SDHCI_CLOCK_CONTROL);
+	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
 
-	if (clock == 0) {
-		sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
+	if (clock == 0)
 		return;
-	}
 
 	clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
 	sdhci_enable_clk(host, clk);