meta-ethanolx: switch u-boot to 2019.04

Switch the u-boot branch from the 2016.07-aspeed-openbmc
to the 2019.04-aspeed-openbmc.

Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
Change-Id: I7f17b31abe32c374b01cb037ba03ed2608c1190d
diff --git a/meta-amd/meta-ethanolx/conf/machine/ethanolx.conf b/meta-amd/meta-ethanolx/conf/machine/ethanolx.conf
index bc62aec..dd6ef51 100644
--- a/meta-amd/meta-ethanolx/conf/machine/ethanolx.conf
+++ b/meta-amd/meta-ethanolx/conf/machine/ethanolx.conf
@@ -2,11 +2,8 @@
 KMACHINE = "aspeed"
 KERNEL_DEVICETREE = "${KMACHINE}-bmc-amd-${MACHINE}.dtb"
 
-PREFERRED_PROVIDER_virtual/bootloader = "u-boot-aspeed"
-PREFERRED_PROVIDER_u-boot = "u-boot-aspeed"
-PREFERRED_PROVIDER_u-boot-fw-utils = "u-boot-fw-utils-aspeed"
-
-UBOOT_MACHINE:ethanolx = "ast_g5_phy_config"
+UBOOT_DEVICETREE = "ast2500-evb"
+UBOOT_MACHINE = "evb-ast2500_defconfig"
 
 require conf/machine/include/ast2500.inc
 require conf/machine/include/obmc-bsp-common.inc