mmc: sdhci: add card_event callback to sdhci

Add a card_event callback to sdhci so that clients can provide their
own card_event to be called when card_detect is triggered.

Signed-off-by: Christian Daudt <csd@broadcom.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 379e09d..b037f18 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -294,6 +294,7 @@
 	void	(*platform_resume)(struct sdhci_host *host);
 	void    (*adma_workaround)(struct sdhci_host *host, u32 intmask);
 	void	(*platform_init)(struct sdhci_host *host);
+	void    (*card_event)(struct sdhci_host *host);
 };
 
 #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS