Convert CONFIG_CMD_SATA to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_SATA

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/configs/db-mv784mp-gp_defconfig b/configs/db-mv784mp-gp_defconfig
index 9e7e89e..99533b9 100644
--- a/configs/db-mv784mp-gp_defconfig
+++ b/configs/db-mv784mp-gp_defconfig
@@ -21,6 +21,7 @@
 CONFIG_CMD_SPI=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_USB=y
+CONFIG_CMD_SATA=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_TFTPPUT=y
 CONFIG_CMD_DHCP=y