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/drivers/dma/bestcomm/sram.c b/drivers/dma/bestcomm/sram.c
index 5e2ed30..2074e0e 100644
--- a/drivers/dma/bestcomm/sram.c
+++ b/drivers/dma/bestcomm/sram.c
@@ -19,6 +19,7 @@
 #include <linux/string.h>
 #include <linux/ioport.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 
 #include <asm/io.h>
 #include <asm/mmu.h>