macintosh/macio-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/1647509089-4280-1-git-send-email-baihaowen@meizu.com

drivers/macintosh/macio-adb.c

@@ -100,7 +100,7 @@ int macio_init(void)
 	unsigned int irq;
 
 	adbs = of_find_compatible_node(NULL, "adb", "chrp,adb0");
-	if (adbs == 0)
+	if (!adbs)
 		return -ENXIO;
 
 	if (of_address_to_resource(adbs, 0, &r)) {
@@ -183,7 +183,7 @@ static int macio_send_request(struct adb_request *req, int sync)
 	req->reply_len = 0;
 
 	spin_lock_irqsave(&macio_lock, flags);
-	if (current_req != 0) {
+	if (current_req) {
 		last_req->next = req;
 		last_req = req;
 	} else {
@@ -213,7 +213,8 @@ static irqreturn_t macio_adb_interrupt(int irq, void *arg)
 	spin_lock(&macio_lock);
 	if (in_8(&adb->intr.r) & TAG) {
 		handled = 1;
-		if ((req = current_req) != 0) {
+		req = current_req;
+		if (req) {
 			/* put the current request in */
 			for (i = 0; i < req->nbytes; ++i)
 				out_8(&adb->data[i].r, req->data[i]);