xes: Consolidate checkboard()

Create a common checkboard() function to support all X-ES's Freescale
boards.

Also, add a get_board_derivative() function which reads hardware
strapping resistors to determine what model a board is.  This allows one
U-Boot image to support multiple boards.

Signed-off-by: John Schmoller <jschmoller@xes-inc.com>
Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/include/configs/XPEDITE5370.h b/include/configs/XPEDITE5370.h
index 73e3d52..9b0ac4b 100644
--- a/include/configs/XPEDITE5370.h
+++ b/include/configs/XPEDITE5370.h
@@ -36,6 +36,7 @@
 #define CONFIG_MPC8572		1
 #define CONFIG_XPEDITE5370	1
 #define CONFIG_SYS_BOARD_NAME	"XPedite5370"
+#define CONFIG_SYS_FORM_3U_VPX	1
 #define CONFIG_BOARD_EARLY_INIT_R	/* Call board_pre_init */
 
 #ifndef CONFIG_SYS_TEXT_BASE