mmc: Add bcm2835 sdhost controller

The BCM2835 family of SoCs has 2 different SD controllers: One based on
the SDHCI spec and a custom, home-grown one.

This patch implements a driver for the latter based on the Linux driver.
This is needed so that we can make use of device trees that assume driver
presence of both SD controllers.

Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/drivers/mmc/Makefile b/drivers/mmc/Makefile
index 64b6f21..42113e2 100644
--- a/drivers/mmc/Makefile
+++ b/drivers/mmc/Makefile
@@ -64,3 +64,4 @@
 
 obj-$(CONFIG_MMC_SUNXI)			+= sunxi_mmc.o
 obj-$(CONFIG_MMC_UNIPHIER)		+= uniphier-sd.o
+obj-$(CONFIG_MMC_BCM2835)		+= bcm2835_sdhost.o