wl12xx: use kstrtoul functions

Use the new kstrtoul functions instead of the deprecated strict_strtoul().

Signed-off-by: Luciano Coelho <coelho@ti.com>
diff --git a/drivers/net/wireless/wl12xx/main.c b/drivers/net/wireless/wl12xx/main.c
index 7126506..a5a5d01 100644
--- a/drivers/net/wireless/wl12xx/main.c
+++ b/drivers/net/wireless/wl12xx/main.c
@@ -3397,8 +3397,7 @@
 	unsigned long res;
 	int ret;
 
-	ret = strict_strtoul(buf, 10, &res);
-
+	ret = kstrtoul(buf, 10, &res);
 	if (ret < 0) {
 		wl1271_warning("incorrect value written to bt_coex_mode");
 		return count;