ARM: prima2_defconfig: enable build for SiRFSoC SDHC host

this patch enables the MMC/SDHCI driver for SiRFSoC platforms.
Signed-off-by: NBarry Song <Baohua.Song@csr.com>

arch/arm/configs/prima2_defconfig

@@ -42,6 +42,7 @@ CONFIG_USB_MASS_STORAGE=m
 CONFIG_MMC=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_PLTFM=y
+CONFIG_MMC_SDHCI_SIRF=y
 CONFIG_DMADEVICES=y
 CONFIG_DMADEVICES_DEBUG=y
 CONFIG_DMADEVICES_VDEBUG=y