hafnium: Exclude from world builds

This does not build with clang from meta-clang and also does not build
with gcc either

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

meta-arm/recipes-bsp/hafnium/hafnium_2.7.bb

@@ -77,3 +77,5 @@ python() {
     if d.getVar("BUILD_ARCH") != "x86_64":
         raise bb.parse.SkipRecipe("Cannot be built on non-x86-64 hosts")
 }
+
+EXCLUDE_FROM_WORLD = "1"