NAND boot: MPC8313ERDB support

Note that with older board revisions, NAND boot may only work after a
power-on reset, and not after a warm reset.  I don't have a newer board
to test on; if you have a board with a 33MHz crystal, please let me know
if it works after a warm reset.

Signed-off-by: Scott Wood <scottwood@freescale.com>
diff --git a/nand_spl/nand_boot.c b/nand_spl/nand_boot.c
index 5914d04..0f56ba5 100644
--- a/nand_spl/nand_boot.c
+++ b/nand_spl/nand_boot.c
@@ -235,7 +235,7 @@
 	struct nand_chip nand_chip;
 	nand_info_t nand_info;
 	int ret;
-	void (*uboot)(void);
+	__attribute__((noreturn)) void (*uboot)(void);
 
 	/*
 	 * Init board specific nand support
@@ -254,6 +254,6 @@
 	/*
 	 * Jump to U-Boot image
 	 */
-	uboot = (void (*)(void))CFG_NAND_U_BOOT_START;
+	uboot = (void *)CFG_NAND_U_BOOT_START;
 	(*uboot)();
 }