Add IPL observer support for RaptorCS Blackbird

Signed-off-by: Stewart Smith <stewart@flamingspork.com>
diff --git a/openpower/configs/blackbird_defconfig b/openpower/configs/blackbird_defconfig
index daa1fe0..d2fb5cd 100644
--- a/openpower/configs/blackbird_defconfig
+++ b/openpower/configs/blackbird_defconfig
@@ -1,5 +1,6 @@
 BR2_powerpc64le=y
 BR2_powerpc_power8=y
+BR2_GLOBAL_PATCH_DIR="$(BR2_EXTERNAL_OP_BUILD_PATH)/patches/blackbird-patches"
 BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_4=y
 BR2_BINUTILS_EXTRA_CONFIG_OPTIONS="--enable-targets=powerpc64-linux"
 BR2_GCC_VERSION_6_X=y