IOMUX: Split out for_each_console_dev() helper macro

It is not only less lines of code, but also better readability
when new macro is being in use. Introduce for_each_console_dev()
helper macro and convert current users to it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
diff --git a/common/iomux.c b/common/iomux.c
index a8be1ac..5290b13 100644
--- a/common/iomux.c
+++ b/common/iomux.c
@@ -15,10 +15,8 @@
 	int i;
 	struct stdio_dev *dev;
 
-	for (i = 0; i < cd_count[console]; i++) {
-		dev = console_devices[console][i];
+	for_each_console_dev(i, console, dev)
 		printf("%s ", dev->name);
-	}
 	printf("\n");
 }