hptmv: remove vestigial EVENTHANDLER_DEREGISTER()

The registration was removed in favor of DEVICE_SHUTDOWN(). Drop the
unused eventhandler tag from the IAL_ADAPTER_T structure.

Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Fixes:	cd3ef66680 ("Use DEVICE_SHUTDOWN(9) mechanism...")
Differential Revision:	https://reviews.freebsd.org/D42334

sys/dev/hptmv/entry.c

@@ -2155,7 +2155,6 @@ hpt_shutdown(device_t dev)
 	
 		pAdapter = device_get_softc(dev);
 
-		EVENTHANDLER_DEREGISTER(shutdown_final, pAdapter->eh);
 		mtx_lock(&pAdapter->lock);
 		FlushAdapter(pAdapter);
 		mtx_unlock(&pAdapter->lock);

sys/dev/hptmv/osbsd.h

@@ -190,8 +190,6 @@ typedef struct IALAdapter
 	UCHAR               status;
 	UCHAR               ver_601;
 	UCHAR               beeping;
-
-	eventhandler_tag	eh;
 }
 IAL_ADAPTER_T;