AST2400: Use Palmetto as the default uboot target

An evaluation board target would be nice here but at least Palmetto is
an improvement over the generic ARM target.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-ast2400/conf/machine/include/ast2400.inc b/meta-ast2400/conf/machine/include/ast2400.inc
index 97a8834..964de9a 100644
--- a/meta-ast2400/conf/machine/include/ast2400.inc
+++ b/meta-ast2400/conf/machine/include/ast2400.inc
@@ -5,7 +5,7 @@
 PREFERRED_PROVIDER_virtual/kernel ?= "linux-obmc"
 PREFERRED_VERSION_linux-obmc ?= "4.4+git%"
 
-UBOOT_MACHINE ?= "versatileab_config"
+UBOOT_MACHINE ?= "palmetto_config"
 UBOOT_ENTRYPOINT ?= "0x40001000"
 UBOOT_LOADADDRESS ?= "0x40001000"