mmc: sdhci: remove comment regarding timeout during tuning

Since commit 7ce45e950624 ("mmc: sdhci: SD tuning is broken for some
controllers") sdhci_execute_tuning() no longer includes a timeout in its
loop counter(s) so remove portion of the comment regarding this.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci.c

@@ -1909,7 +1909,7 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 
 	/*
 	 * Issue CMD19 repeatedly till Execute Tuning is set to 0 or the number
-	 * of loops reaches 40 times or a timeout of 150ms occurs.
+	 * of loops reaches 40 times.
 	 */
 	do {
 		struct mmc_command cmd = {0};