Fix incorrect use of getenv() before relocation

A large number of boards incorrectly used getenv() in their board init
code running before relocation.  In some cases this caused U-Boot to
hang when certain environment variables grew too long.
Fix the code to use getenv_r().

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: The LEOX team <team@leox.org>
Cc: Michael Schwingen <michael@schwingen.org>
Cc: Georg Schardt <schardt@team-ctech.de>
Cc: Werner Pfister <Pfister_Werner@intercontrol.de>
Cc: Dirk Eibach <eibach@gdsys.de>
Cc: Peter De Schrijver <p2@mind.be>
Cc: John Zhan <zhanz@sinovee.com>
Cc: Rishi Bhattacharya <rishi@ti.com>
Cc: Peter Tyser <ptyser@xes-inc.com>
diff --git a/board/c2mon/c2mon.c b/board/c2mon/c2mon.c
index 717a64b..348dfa0 100644
--- a/board/c2mon/c2mon.c
+++ b/board/c2mon/c2mon.c
@@ -91,14 +91,16 @@
 
 int checkboard (void)
 {
-	unsigned char *s = (unsigned char *)getenv ("serial#");
+	char buf[64];
+	int i;
+	int l = getenv_f("serial#", buf, sizeof(buf));
 
 	puts ("Board: TTTech C2MON ");
 
-	for (; s && *s; ++s) {
-		if (*s == ' ')
+	for (i = 0; i < l;  ++i) {
+		if (buf[i] == ' ')
 			break;
-		putc (*s);
+		putc (buf[i]);
 	}
 
 	putc ('\n');