drivers: clean-up prom.h implicit includes

Powerpc is a mess of implicit includes by prom.h. Add the necessary
explicit includes to drivers in preparation of prom.h cleanup.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Grant Likely <grant.likely@linaro.org>
diff --git a/sound/aoa/core/gpio-feature.c b/sound/aoa/core/gpio-feature.c
index faa3174..f341539 100644
--- a/sound/aoa/core/gpio-feature.c
+++ b/sound/aoa/core/gpio-feature.c
@@ -10,8 +10,9 @@
  * registers.
  */
 
-#include <asm/pmac_feature.h>
+#include <linux/of_irq.h>
 #include <linux/interrupt.h>
+#include <asm/pmac_feature.h>
 #include "../aoa.h"
 
 /* TODO: these are lots of global variables