MIPS: FW: Use kstrtoul() to parse unsigned long from the fw environment

Fix some value corruptions with values that can't be represented in a
signed long.
Signed-off-by: Alban Bedel <albeu@free.fr>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8358/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/fw/lib/cmdline.c

@@ -88,13 +88,13 @@ unsigned long fw_getenvl(char *envname)
 {
 	unsigned long envl = 0UL;
 	char *str;
-	long val;
 	int tmp;
 
 	str = fw_getenv(envname);
 	if (str) {
-		tmp = kstrtol(str, 0, &val);
-		envl = (unsigned long)val;
+		tmp = kstrtoul(str, 0, &envl);
+		if (tmp)
+			envl = 0;
 	}
 
 	return envl;