ata: Migrate CONFIG_DWC_AHSATA to Kconfig

Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
diff --git a/configs/dh_imx6_defconfig b/configs/dh_imx6_defconfig
index 814df1c..1fd7c50 100644
--- a/configs/dh_imx6_defconfig
+++ b/configs/dh_imx6_defconfig
@@ -40,6 +40,7 @@
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
 CONFIG_ENV_IS_IN_SPI_FLASH=y
+CONFIG_DWC_AHSATA=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_PHYLIB=y