u-boot: Upgrade AST2400 machines to 2016.05 tree.

Move 2016.05 tree to point at the latest openbmc commit and point
all AST2400 machines to it.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/meta-garrison/conf/machine/garrison.conf b/meta-garrison/conf/machine/garrison.conf
index 4fd03fd..820a513 100644
--- a/meta-garrison/conf/machine/garrison.conf
+++ b/meta-garrison/conf/machine/garrison.conf
@@ -5,7 +5,7 @@
 require conf/machine/include/obmc-bsp-common.inc
 require conf/machine/include/ibm.inc
 
-UBOOT_MACHINE_garrison = "palmetto_config"
+UBOOT_MACHINE_garrison = "ast_g4_config"
 UBOOT_ENTRYPOINT = "0x40008000"
 UBOOT_LOADADDRESS = "0x40008000"