mmc: Add support for Qualcomm SDHCI controller

Add support for SD/eMMC controller present on some Qualcomm Snapdragon
devices. This controller implements SDHCI 2.0 interface but requires
vendor-specific initialization.
Driver works in PIO mode as ADMA is not supported by U-Boot (yet).

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/mmc/Makefile b/drivers/mmc/Makefile
index b85e4bf..585aaf3 100644
--- a/drivers/mmc/Makefile
+++ b/drivers/mmc/Makefile
@@ -50,3 +50,4 @@
 obj-$(CONFIG_GENERIC_MMC) += mmc_write.o
 endif
 obj-$(CONFIG_PIC32_SDHCI) += pic32_sdhci.o
+obj-$(CONFIG_MSM_SDHCI) += msm_sdhci.o