MMC: Do not use mmc_debug if CONFIG_MMC_BCM2835 is not set

If CONFIG_MMC_BCM2835 was not set the compiling of the kernel failed
since mmc_debug was not defined but used in drivers/mmc/core/quirks.c.

This patch add a ifdef-check for CONFIG_MMC_BCM2835 to the change of
commit 64d3954

Author: JanLuca

drivers/mmc/core/quirks.c

@@ -53,7 +53,9 @@ static const struct mmc_fixup mmc_fixup_methods[] = {
 
 void mmc_fixup_device(struct mmc_card *card, const struct mmc_fixup *table)
 {
+#ifdef CONFIG_MMC_BCM2835
 	extern unsigned mmc_debug;
+#endif
 	const struct mmc_fixup *f;
 	u64 rev = cid_rev_card(card);
 
@@ -81,7 +83,9 @@ void mmc_fixup_device(struct mmc_card *card, const struct mmc_fixup *table)
 	/* SDHCI on BCM2708 - bug causes a certain sequence of CMD23 operations to fail.
 	 * Disable this flag for all cards (fall-back to CMD25/CMD18 multi-block transfers).
 	 */
+#ifdef CONFIG_MMC_BCM2835
 	if (mmc_debug & (1<<13))
 	card->quirks |= MMC_QUIRK_BLK_NO_CMD23;
+#endif
 }
 EXPORT_SYMBOL(mmc_fixup_device);