hcode: Build stable OP920 branch by default

Much like what's done for hostboot, we use the OP920 branch that's
being used to stabilize P9 platforms for the moment.

Use BR2_HCODE_LATEST_VERSION=y for getting hcode master

Signed-off-by: Stewart Smith <stewart@linux.ibm.com>
diff --git a/openpower/package/hcode/hcode.mk b/openpower/package/hcode/hcode.mk
index 99816a3..f35a363 100644
--- a/openpower/package/hcode/hcode.mk
+++ b/openpower/package/hcode/hcode.mk
@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-HCODE_VERSION ?= 1b068da5e7532c03b43daea4dc268e7de9cd650d
+HCODE_VERSION = $(call qstrip,$(BR2_HCODE_VERSION))
 HCODE_SITE = $(call github,open-power,hcode,$(HCODE_VERSION))
 
 HCODE_LICENSE = Apache-2.0