macintosh/adb: Fix warning comparing pointer to 0

Avoid pointer type value compared with 0 to make code clear.
Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1647484554-13258-1-git-send-email-baihaowen@meizu.com

drivers/macintosh/adb.c

@@ -478,7 +478,7 @@ adb_register(int default_id, int handler_id, struct adb_ids *ids,
 		if ((adb_handler[i].original_address == default_id) &&
 		    (!handler_id || (handler_id == adb_handler[i].handler_id) || 
 		    try_handler_change(i, handler_id))) {
-			if (adb_handler[i].handler != 0) {
+			if (adb_handler[i].handler) {
 				pr_err("Two handlers for ADB device %d\n",
 				       default_id);
 				continue;
@@ -673,7 +673,7 @@ static int adb_open(struct inode *inode, struct file *file)
 		goto out;
 	}
 	state = kmalloc(sizeof(struct adbdev_state), GFP_KERNEL);
-	if (state == 0) {
+	if (!state) {
 		ret = -ENOMEM;
 		goto out;
 	}