mmc: bcm2835: fix 64-bit build warning

Fixes:
drivers/mmc/bcm2835_sdhci.c: In function ‘bcm2835_sdhci_init’:
drivers/mmc/bcm2835_sdhci.c:181:17: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>

drivers/mmc/bcm2835_sdhci.c

@@ -178,7 +178,7 @@ int bcm2835_sdhci_init(u32 regbase, u32 emmc_freq)
 
 	host = &bcm_host->host;
 	host->name = "bcm2835_sdhci";
-	host->ioaddr = (void *)regbase;
+	host->ioaddr = (void *)(unsigned long)regbase;
 	host->quirks = SDHCI_QUIRK_BROKEN_VOLTAGE | SDHCI_QUIRK_BROKEN_R1B |
 		SDHCI_QUIRK_WAIT_SEND_CMD | SDHCI_QUIRK_NO_HISPD_BIT;
 	host->voltages = MMC_VDD_32_33 | MMC_VDD_33_34 | MMC_VDD_165_195;