Add proper debugging infrastructure for acpi_hpet.c.

sys/dev/acpica/acpi_hpet.c

@@ -41,6 +41,10 @@ __FBSDID("$FreeBSD$");
 
 ACPI_SERIAL_DECL(hpet, "ACPI HPET support");
 
+/* ACPI CA debugging */
+#define _COMPONENT	ACPI_HPET
+ACPI_MODULE_NAME("HPET")
+
 struct acpi_hpet_softc {
 	device_t		dev;
 	struct resource		*res[1];

sys/dev/acpica/acpivar.h

@@ -154,6 +154,7 @@ extern struct mtx			acpi_mutex;
 #define	ACPI_THERMAL		0x01000000
 #define	ACPI_TIMER		0x02000000
 #define	ACPI_OEM		0x04000000
+#define	ACPI_HPET		0x08000000
 
 /*
  * Constants for different interrupt models used with acpi_SetIntrModel().