mmc: sdhci: mmc_rescan: reduce verbosity

mmc_rescan() includes a pr_info which prints 4 lines each second for
hosts configured with MMC_CAP_NEEDS_POLL. This patch enables the message
only if CONFIG_MMC_DEBUG is selected. Tested on i.MX51's sdhci-esdhc.

Signed-off-by: Eric Bénard <[e-mail]>
Acked-by: Wolfram Sang <[e-mail]>
Acked-by: Hein Tibosch <[e-mail]>
Signed-off-by: Chris Ball <[e-mail]>

drivers/mmc/core/core.c

···
 			mmc_release_host(host);
 			goto out;
 		}
+#ifdef CONFIG_MMC_DEBUG
 		pr_info("%s: %s: trying to init card at %u Hz\n",
 			mmc_hostname(host), __func__, host->f_init);
-
+#endif
 		mmc_power_up(host);
 		sdio_reset(host);
 		mmc_go_idle(host);