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/XPEDITE5170.h b/include/configs/XPEDITE5170.h
index ab6d4b4..eeae5f0 100644
--- a/include/configs/XPEDITE5170.h
+++ b/include/configs/XPEDITE5170.h
@@ -34,6 +34,7 @@
 #define CONFIG_MPC8641		1	/* MPC8641 specific */
 #define CONFIG_XPEDITE5140	1	/* MPC8641HPCN board specific */
 #define CONFIG_SYS_BOARD_NAME	"XPedite5170"
+#define CONFIG_SYS_FORM_3U_VPX	1
 #define CONFIG_LINUX_RESET_VEC	0x100	/* Reset vector used by Linux */
 #define CONFIG_BOARD_EARLY_INIT_R	/* Call board_pre_init */
 #define CONFIG_BAT_RW		1	/* Use common BAT rw code */