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/cli.c

@@ -12,6 +12,7 @@
 #include <common.h>
 #include <cli.h>
 #include <cli_hush.h>
+#include <console.h>
 #include <fdtdec.h>
 #include <malloc.h>