config: evb-rk3399: enable fixed regulator

This patch enable fixed regulator driver for rk3399 evb.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/evb-rk3399_defconfig b/configs/evb-rk3399_defconfig
index 1f6855c..25e8939 100644
--- a/configs/evb-rk3399_defconfig
+++ b/configs/evb-rk3399_defconfig
@@ -38,3 +38,5 @@
 CONFIG_USB_XHCI_DWC3=y
 CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_EHCI_GENERIC=y
+CONFIG_DM_REGULATOR=y
+CONFIG_DM_REGULATOR_FIXED=y