mmc: detect SDIO cards

Really basic init sequence for SDIO cards.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 29c98ae..8faa436 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -41,6 +41,7 @@
 #define MMC_RSP_R1B	(MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE|MMC_RSP_BUSY)
 #define MMC_RSP_R2	(MMC_RSP_PRESENT|MMC_RSP_136|MMC_RSP_CRC)
 #define MMC_RSP_R3	(MMC_RSP_PRESENT)
+#define MMC_RSP_R4	(MMC_RSP_PRESENT)
 #define MMC_RSP_R6	(MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE)
 #define MMC_RSP_R7	(MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE)