meta-hpe: rl300-g11 add specific u-boot-gxp bbappend

Change-Id: I61fdcaab29a0bcad9f51d3c51bc67401b9356af9
Signed-off-by: Charles Kearney <charles.kearney@hpe.com>
diff --git a/meta-hpe/meta-rl300-g11/conf/machine/rl300-g11.conf b/meta-hpe/meta-rl300-g11/conf/machine/rl300-g11.conf
index ad6922a..91752b8 100644
--- a/meta-hpe/meta-rl300-g11/conf/machine/rl300-g11.conf
+++ b/meta-hpe/meta-rl300-g11/conf/machine/rl300-g11.conf
@@ -1,5 +1,7 @@
 KERNEL_DEVICETREE = "gxp.dtb"
 
+UBOOT_MACHINE = "gxp2_defconfig"
+
 require conf/machine/include/gxp.inc
 require conf/machine/include/obmc-bsp-common.inc
 require conf/machine/include/hpe.inc