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>
diff --git a/board/esd/cpci405/cpci405.c b/board/esd/cpci405/cpci405.c
index bf5a4cb..ca9a944 100644
--- a/board/esd/cpci405/cpci405.c
+++ b/board/esd/cpci405/cpci405.c
@@ -5,6 +5,7 @@
  * SPDX-License-Identifier:	GPL-2.0+
  */
 #include <common.h>
+#include <console.h>
 #include <libfdt.h>
 #include <fdt_support.h>
 #include <asm/processor.h>