MX31: Add NAND SPL boot support to i.MX31 PDK board.

Signed-off-by: Magnus Lilja <lilja.magnus@gmail.com>
diff --git a/board/freescale/mx31pdk/config.mk b/board/freescale/mx31pdk/config.mk
index d34dc02..dcaa09f 100644
--- a/board/freescale/mx31pdk/config.mk
+++ b/board/freescale/mx31pdk/config.mk
@@ -1 +1,5 @@
+ifdef CONFIG_NAND_SPL
+TEXT_BASE = 0x87ec0000
+else
 TEXT_BASE = 0x87f00000
+endif