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/mpl/pati/pati.c b/board/mpl/pati/pati.c
index 958cdec..ddc2108 100644
--- a/board/mpl/pati/pati.c
+++ b/board/mpl/pati/pati.c
@@ -29,6 +29,7 @@
  **********************************************************************************/
 
 #include <common.h>
+#include <console.h>
 #include <mpc5xx.h>
 #include <stdio_dev.h>
 #include <pci_ids.h>