aspeed: evb-ast2600: Use unversioned device tree

The EVB build is currently using the A1 device tree. Use the plain
ast2600-evb.dts, as this represents the production silicon.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Change-Id: Icef427718958bf19ee75fec906cf0476f5d37138
diff --git a/meta-aspeed/conf/machine/evb-ast2600.conf b/meta-aspeed/conf/machine/evb-ast2600.conf
index e0aa2cd..5fbc71e 100644
--- a/meta-aspeed/conf/machine/evb-ast2600.conf
+++ b/meta-aspeed/conf/machine/evb-ast2600.conf
@@ -1,6 +1,7 @@
 KERNEL_DEVICETREE = "aspeed-ast2600-evb.dtb"
+
 UBOOT_MACHINE = "ast2600_openbmc_spl_defconfig"
-UBOOT_DEVICETREE = "ast2600a1-evb"
+UBOOT_DEVICETREE = "ast2600-evb"
 SPL_BINARY = "spl/u-boot-spl.bin"
 
 require conf/machine/include/ast2600.inc