ppc4xx: Fix printf format warnings now visible with the updated format check

This patch fixes ppc4xx related printf format warning. Those warnings are
now visible since patch dc4b0b38d4aadf08826f6c31270f1eecd27964fd
[Fix printf errors.] by Andrew Klossner has been applied. Thanks, this is
really helpful.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/board/lwmon5/sdram.c b/board/lwmon5/sdram.c
index 0a13831..189e824 100644
--- a/board/lwmon5/sdram.c
+++ b/board/lwmon5/sdram.c
@@ -84,7 +84,7 @@
 		puts(" (ECC not");
 
 	get_sys_info(&board_cfg);
-	printf(" enabled, %d MHz", (board_cfg.freqPLB * 2) / 1000000);
+	printf(" enabled, %ld MHz", (board_cfg.freqPLB * 2) / 1000000);
 
 	mfsdram(DDR0_03, val);
 	val = DDR0_03_CASLAT_DECODE(val);