kern: ofw: provide ofw_bus_destroy_iinfo to teardown interrupt-map

For symmetry with ofw_bus_setup_iinfo, the next commits will use it to
properly cleanup on failure in bcm2838_pci.

Reviewed by:	andrew
Differential Revision:	https://reviews.freebsd.org/D56895

sys/dev/ofw/ofw_bus_subr.c

@@ -358,6 +358,18 @@ ofw_bus_setup_iinfo(phandle_t node, struct ofw_bus_iinfo *ii, int intrsz)
 	}
 }
 
+void
+ofw_bus_destroy_iinfo(struct ofw_bus_iinfo *ii)
+{
+
+	if (ii->opi_imapsz > 0) {
+		OF_prop_free(ii->opi_imapmsk);
+		ii->opi_imapsz = 0;
+	}
+
+	OF_prop_free(ii->opi_imap);
+}
+
 int
 ofw_bus_lookup_imap(phandle_t node, struct ofw_bus_iinfo *ii, void *reg,
     int regsz, void *pintr, int pintrsz, void *mintr, int mintrsz,

sys/dev/ofw/ofw_bus_subr.h

@@ -86,6 +86,7 @@ bus_get_device_path_t	ofw_bus_gen_get_device_path;
 
 /* Routines for processing firmware interrupt maps */
 void	ofw_bus_setup_iinfo(phandle_t, struct ofw_bus_iinfo *, int);
+void	ofw_bus_destroy_iinfo(struct ofw_bus_iinfo *);
 int	ofw_bus_lookup_imap(phandle_t, struct ofw_bus_iinfo *, void *, int,
 	    void *, int, void *, int, phandle_t *);
 int	ofw_bus_search_intrmap(void *, int, void *, int, void *, int, void *,