ata: DWC_AHSATA depends on BLK

The dwc ahsata driver is written such that CONFIG_BLK must be enabled,
add this as a dependency in Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index f2f8275..3914f99 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -62,6 +62,7 @@
 config DWC_AHSATA
 	bool "Enable DWC AHSATA driver support"
 	select LIBATA
+	depends on BLK
 	help
 	  Enable this driver to support the DWC AHSATA SATA controller found
 	  in i.MX5 and i.MX6 SoCs.