[POWERPC] powerpc: fix build error in rom.c

Add missing include in rom.c. Fixes this build error when CONFIG_MTD=y:

arch/powerpc/sysdev/rom.c:26: error: implicit declaration of function
of_platform_device_create

Signed-off-by: Geoff Levand <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/powerpc/sysdev/rom.c

···
 
 #include <linux/kernel.h>
 #include <asm/of_device.h>
+#include <asm/of_platform.h>
 
 static int __init powerpc_flash_init(void)
 {