ida: Use ida lock instead of Giant for bus_dma allocation

It looks like a reference to Giant was overloooked when jhb made this
MPSAFE in 6b5b57ae9f.

Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D31841

sys/dev/ida/ida.c

@@ -248,7 +248,7 @@ ida_setup(struct ida_softc *ida)
 		/* maxsegsz	*/ BUS_SPACE_MAXSIZE_32BIT,
 		/* flags	*/ 0,
 		/* lockfunc	*/ busdma_lock_mutex,
-		/* lockarg	*/ &Giant,
+		/* lockarg	*/ &ida->lock,
 		&ida->buffer_dmat);
 	if (error)
 		return (ENOMEM);