mmc: sdhci-of-arasan: Fix non static symbol warning

Fixes the following sparse warning:

drivers/mmc/host/sdhci-of-arasan.c:253:6: warning:
 symbol 'sdhci_arasan_reset' was not declared. Should it be static?
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-of-arasan.c

@@ -250,7 +250,7 @@ static void sdhci_arasan_hs400_enhanced_strobe(struct mmc_host *mmc,
 	writel(vendor, host->ioaddr + SDHCI_ARASAN_VENDOR_REGISTER);
 }
 
-void sdhci_arasan_reset(struct sdhci_host *host, u8 mask)
+static void sdhci_arasan_reset(struct sdhci_host *host, u8 mask)
 {
 	u8 ctrl;
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);