u-boot: Specify u-boot package for AST2400 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.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Change-Id: Iaf709343b966c39ca707a10ef57fa0010bf6eb6f
diff --git a/meta-ibm/meta-palmetto/conf/machine/palmetto.conf b/meta-ibm/meta-palmetto/conf/machine/palmetto.conf
index 6f0e905..bd70c5e 100644
--- a/meta-ibm/meta-palmetto/conf/machine/palmetto.conf
+++ b/meta-ibm/meta-palmetto/conf/machine/palmetto.conf
@@ -6,6 +6,10 @@
 require conf/machine/include/openpower.inc
 require conf/machine/include/p8.inc
 
+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:palmetto = "ast_g4_ncsi_config"
 UBOOT_ENTRYPOINT = "0x40008000"
 UBOOT_LOADADDRESS = "0x40008000"