dm: mmc: rpi: Convert Raspberry Pi to driver model for MMC

Convert the bcm2835 SDHCI driver over to support CONFIG_DM_MMC and move
all boards over. There is no need to keep the old code since there are no
other users.

Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/rpi_3_32b_defconfig b/configs/rpi_3_32b_defconfig
index 306d54f..ab58045 100644
--- a/configs/rpi_3_32b_defconfig
+++ b/configs/rpi_3_32b_defconfig
@@ -15,6 +15,7 @@
 # CONFIG_CMD_FPGA is not set
 CONFIG_CMD_GPIO=y
 CONFIG_OF_EMBED=y
+CONFIG_DM_MMC=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_BCM2835=y
 CONFIG_DM_ETH=y