powerpc/powermac: Drop unnecessary null test

for_each_node_by_name binds its first argument to a non-null value, and
thus any null test on the value of that argument is superfluous.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
iterator I;
expression x,E;
@@

I(x,...) { <...
(
- (x != NULL) &&
  E
  ...> }
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/powermac/feature.c

@@ -2873,7 +2873,7 @@ set_initial_features(void)
 
 		/* Switch airport off */
 		for_each_node_by_name(np, "radio") {
-			if (np && np->parent == macio_chips[0].of_node) {
+			if (np->parent == macio_chips[0].of_node) {
 				macio_chips[0].flags |= MACIO_FLAG_AIRPORT_ON;
 				core99_airport_enable(np, 0, 0);
 			}