powerpc/85xx/ge_imp3a: Don't use the flat device-tree after boot

ge_imp3a_pic_init() is called way beyond the unflattening of
the tree, it shouldn't be using of_flat_dt_*
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/85xx/ge_imp3a.c

@@ -47,9 +47,8 @@ void __init ge_imp3a_pic_init(void)
 	struct mpic *mpic;
 	struct device_node *np;
 	struct device_node *cascade_node = NULL;
-	unsigned long root = of_get_flat_dt_root();
 
-	if (of_flat_dt_is_compatible(root, "fsl,MPC8572DS-CAMP")) {
+	if (of_machine_is_compatible("fsl,MPC8572DS-CAMP")) {
 		mpic = mpic_alloc(NULL, 0,
 			MPIC_NO_RESET |
 			MPIC_BIG_ENDIAN |