mmc: sdhci-bcm-kona: Staticize sdhci_bcm_kona_card_event

sdhci_bcm_kona_card_event is referenced only in this file.
Make it static.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Christian Daudt <csd@broadcom.com>

drivers/mmc/host/sdhci-bcm-kona.c

@@ -161,7 +161,7 @@ static int sdhci_bcm_kona_sd_card_emulate(struct sdhci_host *host, int insert)
 /*
  * SD card interrupt event callback
  */
-void sdhci_bcm_kona_card_event(struct sdhci_host *host)
+static void sdhci_bcm_kona_card_event(struct sdhci_host *host)
 {
 	if (mmc_gpio_get_cd(host->mmc) > 0) {
 		dev_dbg(mmc_dev(host->mmc),