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/astro/mcf5373l/fpga.c b/board/astro/mcf5373l/fpga.c
index d1110df..53e0072 100644
--- a/board/astro/mcf5373l/fpga.c
+++ b/board/astro/mcf5373l/fpga.c
@@ -15,6 +15,7 @@
 /* Altera/Xilinx FPGA configuration support for the ASTRO "URMEL" board */
 
 #include <common.h>
+#include <console.h>
 #include <watchdog.h>
 #include <altera.h>
 #include <ACEX1K.h>