mx6sabresd: Remove unneeded checkboard()

After the conversion to device tree the board information becomes
redundant:

Model: Freescale i.MX6 Quad Plus SABRE Smart Device Board
Board: MX6-SabreSD

Remove the printing of the board information.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/board/freescale/mx6sabresd/mx6sabresd.c b/board/freescale/mx6sabresd/mx6sabresd.c
index 0d343da..9a176f4 100644
--- a/board/freescale/mx6sabresd/mx6sabresd.c
+++ b/board/freescale/mx6sabresd/mx6sabresd.c
@@ -575,12 +575,6 @@
 	return 0;
 }
 
-int checkboard(void)
-{
-	puts("Board: MX6-SabreSD\n");
-	return 0;
-}
-
 #ifdef CONFIG_SPL_BUILD
 #include <asm/arch/mx6-ddr.h>
 #include <spl.h>