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 <[e-mail]>
Signed-off-by: Chen Zhou <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/ata/pata_macio.c

···
 	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;
 }