u-boot: Specify u-boot package for AST2500 machines

This sets u-boot to the package containing the v2016.07-aspeed-openbmc
branch. This ensures there will be no change if the default changes in
the future.

Change-Id: Iea12e1691dbdda34a3f95d6d0862add0b15bcf37
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/meta-amd/meta-ethanolx/conf/machine/ethanolx.conf b/meta-amd/meta-ethanolx/conf/machine/ethanolx.conf
index 91ca5bb..67fc64c 100644
--- a/meta-amd/meta-ethanolx/conf/machine/ethanolx.conf
+++ b/meta-amd/meta-ethanolx/conf/machine/ethanolx.conf
@@ -2,6 +2,10 @@
 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"
 
 require conf/machine/include/ast2500.inc