Move console definitions into a new console.h file

The console includes a global variable and several functions that are only
used by a small subset of U-Boot files. Before adding more functions, move
the definitions into their own header file.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/board_f.c

@@ -13,6 +13,7 @@
 #include <common.h>
 #include <linux/compiler.h>
 #include <version.h>
+#include <console.h>
 #include <environment.h>
 #include <dm.h>
 #include <fdtdec.h>