mmc: omap: remove unused struct component card_detect_irq

I have not found any user for this struct component.
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Link: https://lore.kernel.org/r/b6f2168b863e4273c6bca5a22fbd4a3a8ddf68d6.1608714110.git.hns@goldelico.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

include/linux/platform_data/mmc-omap.h

@@ -108,8 +108,7 @@ struct omap_mmc_platform_data {
 		const char *name;
 		u32 ocr_mask;
 
-		/* Card detection IRQs */
-		int card_detect_irq;
+		/* Card detection */
 		int (*card_detect)(struct device *dev, int slot);
 
 		unsigned int ban_openended:1;