Switch to little-endian buildroot

This change switches the default toolchain target to little-endian, so
we're able to build buildroot packages as LE.

Firmware components (skiboot, hostboot, etc) are kept as BE, so we
compile the toolchain as biarch.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
diff --git a/openpower/configs/habanero_defconfig b/openpower/configs/habanero_defconfig
index 59ae12c..756f60f 100644
--- a/openpower/configs/habanero_defconfig
+++ b/openpower/configs/habanero_defconfig
@@ -1,7 +1,12 @@
-BR2_powerpc64=y
+BR2_powerpc64le=y
 BR2_powerpc_power8=y
 BR2_OPENPOWER_PLATFORM=y
 
+BR2_BINUTILS_EXTRA_CONFIG_OPTIONS="--enable-targets=powerpc64-linux"
+BR2_EXTRA_GCC_CONFIG_OPTIONS="--enable-targets=powerpc64-linux"
+BR2_TOOLCHAIN_BUILDROOT_CXX=y
+# BR2_TOOLCHAIN_BUILDROOT_LIBSTDCPP is not set
+
 BR2_OPENPOWER_CONFIG_NAME="habanero"
 BR2_OPENPOWER_XML_PACKAGE="habanero-xml"
 BR2_HOSTBOOT_CONFIG_FILE="habanero.config"