of/dynamic: Fix test for PPC_PSERIES

"IS_ENABLED(PPC_PSERIES)" always evaluates to false, as IS_ENABLED() is
supposed to be used with the full Kconfig symbol name, including the
"CONFIG_" prefix.

Add the missing "CONFIG_" prefix to fix this.

Fixes: a25095d4 ("of: Move dynamic node fixups out of powerpc and into common code")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: stable@vger.kernel.org #+3.17
Signed-off-by: Grant Likely <grant.likely@linaro.org>

drivers/of/dynamic.c

@@ -225,7 +225,7 @@ void __of_attach_node(struct device_node *np)
 	phandle = __of_get_property(np, "phandle", &sz);
 	if (!phandle)
 		phandle = __of_get_property(np, "linux,phandle", &sz);
-	if (IS_ENABLED(PPC_PSERIES) && !phandle)
+	if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
 		phandle = __of_get_property(np, "ibm,phandle", &sz);
 	np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;