phylib: simplify NULL checks

Fix scripts/checkpatch.pl's messages like:

CHECK: Comparison to NULL could be written "!phydrv->read_mmd_indirect"

BTW, it doesn't detect the reversed comparisons (which I've fixed as well).
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -1040,7 +1040,7 @@ int phy_read_mmd_indirect(struct phy_device *phydev, int prtad,
 	struct phy_driver *phydrv = phydev->drv;
 	int value = -1;
 
-	if (phydrv->read_mmd_indirect == NULL) {
+	if (!phydrv->read_mmd_indirect) {
 		struct mii_bus *bus = phydev->bus;
 
 		mutex_lock(&bus->mdio_lock);
@@ -1077,7 +1077,7 @@ void phy_write_mmd_indirect(struct phy_device *phydev, int prtad,
 {
 	struct phy_driver *phydrv = phydev->drv;
 
-	if (phydrv->write_mmd_indirect == NULL) {
+	if (!phydrv->write_mmd_indirect) {
 		struct mii_bus *bus = phydev->bus;
 
 		mutex_lock(&bus->mdio_lock);

drivers/net/phy/phy_device.c

@@ -156,7 +156,7 @@ struct phy_device *phy_device_create(struct mii_bus *bus, int addr, int phy_id,
 
 	/* We allocate the device, and initialize the default values */
 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
-	if (NULL == dev)
+	if (!dev)
 		return ERR_PTR(-ENOMEM);
 
 	dev->dev.release = phy_device_release;
@@ -178,7 +178,7 @@ struct phy_device *phy_device_create(struct mii_bus *bus, int addr, int phy_id,
 	dev->bus = bus;
 	dev->dev.parent = &bus->dev;
 	dev->dev.bus = &mdio_bus_type;
-	dev->irq = bus->irq != NULL ? bus->irq[addr] : PHY_POLL;
+	dev->irq = bus->irq ? bus->irq[addr] : PHY_POLL;
 	dev_set_name(&dev->dev, PHY_ID_FMT, bus->id, addr);
 
 	dev->state = PHY_DOWN;
@@ -589,7 +589,7 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 	/* Assume that if there is no driver, that it doesn't
 	 * exist, and we should use the genphy driver.
 	 */
-	if (NULL == d->driver) {
+	if (!d->driver) {
 		if (phydev->is_c45)
 			d->driver = &genphy_driver[GENPHY_DRV_10G].driver;
 		else