mmc: fsl_esdhc: Add adapter card type identification support

Add adapter card type identification support by reading
FPGA STAT_PRES1 register SDHC Card ID[0:2] bits. To use this function,
define CONFIG_FSL_ESDHC_ADAPTER_IDENT.

Signed-off-by: Yangbo Lu <yangbo.lu@freescale.com>
Cc: York Sun <yorksun@freescale.com>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
[York Sun: resolve conflicts in README.fsl-esdhc]
Reviewed-by: York Sun <yorksun@freescale.com>
diff --git a/drivers/mmc/mmc_private.h b/drivers/mmc/mmc_private.h
index 16dcf9f..447a700 100644
--- a/drivers/mmc/mmc_private.h
+++ b/drivers/mmc/mmc_private.h
@@ -16,6 +16,9 @@
 			struct mmc_data *data);
 extern int mmc_send_status(struct mmc *mmc, int timeout);
 extern int mmc_set_blocklen(struct mmc *mmc, int len);
+#ifdef CONFIG_FSL_ESDHC_ADAPTER_IDENT
+void mmc_adapter_card_type_ident(void);
+#endif
 
 #ifndef CONFIG_SPL_BUILD