Add witherspoon defconfig, p9 support for hostboot

Opened RTC issues 160270 and 160273 to fix patches that were
added.
diff --git a/openpower/configs/firestone_defconfig b/openpower/configs/firestone_defconfig
index a55280b..708e768 100644
--- a/openpower/configs/firestone_defconfig
+++ b/openpower/configs/firestone_defconfig
@@ -1,6 +1,7 @@
 BR2_powerpc64le=y
 BR2_powerpc_power8=y
 BR2_OPENPOWER_PLATFORM=y
+BR2_OPENPOWER_POWER8=y
 
 BR2_BINUTILS_EXTRA_CONFIG_OPTIONS="--enable-targets=powerpc64-linux"
 BR2_EXTRA_GCC_CONFIG_OPTIONS="--enable-targets=powerpc64-linux"