Add witherspoon defconfig, p9 support for hostboot

Opened RTC issues 160270 and 160273 to fix patches that were
added.
diff --git a/openpower/package/skiboot/Config.in b/openpower/package/skiboot/Config.in
index 446805f..cb19c76 100644
--- a/openpower/package/skiboot/Config.in
+++ b/openpower/package/skiboot/Config.in
@@ -3,9 +3,9 @@
 config BR2_PACKAGE_SKIBOOT
 	bool "skiboot"
 	depends on BR2_powerpc64 || BR2_powerpc64le
-        default y if (BR2_OPENPOWER_PLATFORM && BR2_powerpc_power8)
+        default y if (BR2_OPENPOWER_PLATFORM)
 	help
-	  Build skiboot POWER8 firmware
+	  Build skiboot POWER firmware
 
 if BR2_PACKAGE_SKIBOOT