mmc: detect SDIO cards

Really basic init sequence for SDIO cards.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/MAINTAINERS b/MAINTAINERS
index 9a91d9e..c22d34b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2561,7 +2561,7 @@
 W:	http://www.atnf.csiro.au/~rgooch/linux/kernel-patches.html
 S:	Maintained
 
-MULTIMEDIA CARD (MMC) AND SECURE DIGITAL (SD) SUBSYSTEM
+MULTIMEDIA CARD (MMC), SECURE DIGITAL (SD) AND SDIO SUBSYSTEM
 P:	Pierre Ossman
 M:	drzeus-mmc@drzeus.cx
 L:	linux-kernel@vger.kernel.org