Fix various compiler warnings on ppc4xx builds (ELDK 4.0)

Patch by Stefan Roese, 18 Jan 2006
diff --git a/board/esd/vom405/vom405.c b/board/esd/vom405/vom405.c
index 445b8fc..bc5fa7c 100644
--- a/board/esd/vom405/vom405.c
+++ b/board/esd/vom405/vom405.c
@@ -97,7 +97,7 @@
 
 int checkboard (void)
 {
-	unsigned char str[64];
+	char str[64];
 	int i = getenv_r ("serial#", str, sizeof(str));
 	int flashcnt;
 	int delay;