mmc: USB SD Host Controller (USHC) driver

Add a driver for USB SD Host Controller devices.  These devices are
Cypress Astoria chips with firmware compliant with issue 2 of CSR's USHC
specification.

[cjb: adapt to block layer deprecation of max_{hw,phys}_segs]
Signed-off-by: David Vrabel <david.vrabel@csr.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/drivers/mmc/host/Makefile b/drivers/mmc/host/Makefile
index 840bcb5..f7fb7eb 100644
--- a/drivers/mmc/host/Makefile
+++ b/drivers/mmc/host/Makefile
@@ -36,6 +36,7 @@
 obj-$(CONFIG_SDH_BFIN)		+= bfin_sdh.o
 obj-$(CONFIG_MMC_SH_MMCIF)	+= sh_mmcif.o
 obj-$(CONFIG_MMC_JZ4740)	+= jz4740_mmc.o
+obj-$(CONFIG_MMC_USHC)		+= ushc.o
 
 obj-$(CONFIG_MMC_SDHCI_PLTFM)			+= sdhci-platform.o
 sdhci-platform-y				:= sdhci-pltfm.o