main: Use get/setenv_ulong()

These functions are now available, so use them to avoid extra code here.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/common/main.c b/common/main.c
index 159b8e1..38fadac 100644
--- a/common/main.c
+++ b/common/main.c
@@ -352,18 +352,14 @@
 #ifdef CONFIG_BOOTCOUNT_LIMIT
 	unsigned long bootcount = 0;
 	unsigned long bootlimit = 0;
-	char *bcs;
-	char bcs_set[16];
 #endif /* CONFIG_BOOTCOUNT_LIMIT */
 
 #ifdef CONFIG_BOOTCOUNT_LIMIT
 	bootcount = bootcount_load();
 	bootcount++;
 	bootcount_store (bootcount);
-	sprintf (bcs_set, "%lu", bootcount);
-	setenv ("bootcount", bcs_set);
-	bcs = getenv ("bootlimit");
-	bootlimit = bcs ? simple_strtoul (bcs, NULL, 10) : 0;
+	setenv_ulong("bootcount", bootcount);
+	bootlimit = getenv_ulong("bootlimit", 10, 0);
 #endif /* CONFIG_BOOTCOUNT_LIMIT */
 
 	s = getenv ("bootdelay");