sys: Use is_pci_device instead of checking device or devclass names

Reviewed by:	bz, imp
Sponsored by:	Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D56998

sys/dev/sound/pcm/ac97.c

@@ -628,7 +628,7 @@ ac97_initmixer(struct ac97_info *codec)
 	}
 
 	pdev = codec->dev;
-	while (strcmp(device_get_name(device_get_parent(pdev)), "pci") != 0) {
+	while (!is_pci_device(pdev)) {
 		/* find the top-level PCI device handler */
 		pdev = device_get_parent(pdev);
 	}

sys/dev/thunderbolt/tb_pcib.c

@@ -548,16 +548,13 @@ tb_pci_probe(device_t dev)
 {
 	struct tb_pcib_ident *n;
 	device_t parent;
-	devclass_t dc;
 
 	/*
 	 * This driver is only valid if the parent device is a PCI-PCI
-	 * bridge.  To determine that, check if the grandparent is a
-	 * PCI bus.
+	 * bridge.
 	 */
 	parent = device_get_parent(dev);
-	dc = device_get_devclass(device_get_parent(parent));
-	if (strcmp(devclass_get_name(dc), "pci") != 0)
+	if (!is_pci_device(parent))
 		return (ENXIO);
 
 	if ((n = tb_pcib_find_ident(parent)) != NULL) {