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/tqc/tqm8260/tqm8260.c b/board/tqc/tqm8260/tqm8260.c
index 95073b8..65a3174 100644
--- a/board/tqc/tqm8260/tqm8260.c
+++ b/board/tqc/tqm8260/tqm8260.c
@@ -195,17 +195,17 @@
  */
 int checkboard (void)
 {
-	char str[64];
-	int i = getenv_f("serial#", str, sizeof (str));
+	char buf[64];
+	int i = getenv_f("serial#", buf, sizeof(buf));
 
 	puts ("Board: ");
 
-	if (!i || strncmp (str, "TQM82", 5)) {
+	if (i < 0 || strncmp(buf, "TQM82", 5)) {
 		puts ("### No HW ID - assuming TQM8260\n");
 		return (0);
 	}
 
-	puts (str);
+	puts (buf);
 	putc ('\n');
 
 	return 0;