ata: pata_macio: fix comparing pointer to 0

Fixes coccicheck warning:

./drivers/ata/pata_macio.c:982:31-32:
	WARNING comparing pointer to 0, suggest !E

Compare pointer-typed values to NULL rather than 0.
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/ata/pata_macio.c

@@ -979,7 +979,7 @@ static void pata_macio_invariants(struct pata_macio_priv *priv)
 	priv->aapl_bus_id =  bidp ? *bidp : 0;
 
 	/* Fixup missing Apple bus ID in case of media-bay */
-	if (priv->mediabay && bidp == 0)
+	if (priv->mediabay && !bidp)
 		priv->aapl_bus_id = 1;
 }