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/drivers/input/keyboard.c b/drivers/input/keyboard.c
index 71546cb..48255bd 100644
--- a/drivers/input/keyboard.c
+++ b/drivers/input/keyboard.c
@@ -9,7 +9,10 @@
  ***********************************************************************/
 
 #include <common.h>
+#include <console.h>
 #include <input.h>
+
+#include <stdio_dev.h>
 #include <keyboard.h>
 #include <stdio_dev.h>