mmc: sdhci-of-at91: make function sdhci_at91_set_uhs_signaling static

The function sdhci_at91_set_uhs_signaling  is local to the source and does
not need to be in global scope, so make it static.

Cleans up sparse warning:
symbol 'sdhci_at91_set_uhs_signaling' was not declared. Should it be
static?
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-of-at91.c

@@ -114,7 +114,8 @@ static void sdhci_at91_set_power(struct sdhci_host *host, unsigned char mode,
 	sdhci_set_power_noreg(host, mode, vdd);
 }
 
-void sdhci_at91_set_uhs_signaling(struct sdhci_host *host, unsigned int timing)
+static void sdhci_at91_set_uhs_signaling(struct sdhci_host *host,
+					 unsigned int timing)
 {
 	if (timing == MMC_TIMING_MMC_DDR52)
 		sdhci_writeb(host, SDMMC_MC1R_DDR, SDMMC_MC1R);