powerpc: clean the inclusion of stringify.h

Only include linux/stringify.h is files using __stringify()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/powernv/vas.h

@@ -15,6 +15,7 @@
 #include <linux/io.h>
 #include <linux/dcache.h>
 #include <linux/mutex.h>
+#include <linux/stringify.h>
 
 /*
  * Overview of Virtual Accelerator Switchboard (VAS).