[POWERPC] Fix new interrupt code (MPIC endianness)

All U3/U4 based systems are big-endian, not all express it in their
device trees.
Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/maple/setup.c

@@ -252,6 +252,8 @@ static void __init maple_init_IRQ(void)
 
 	/* XXX Maple specific bits */
 	flags |= MPIC_BROKEN_U3 | MPIC_WANTS_RESET;
+	/* All U3/U4 are big-endian, older SLOF firmware doesn't encode this */
+	flags |= MPIC_BIG_ENDIAN;
 
 	/* Setup the openpic driver. More device-tree junks, we hard code no
 	 * ISUs for now. I'll have to revisit some stuffs with the folks doing