dlm: eliminate astparam type casting

Put lkb_astparam in a union with a dlm_user_args pointer to
eliminate a lot of type casting.

Signed-off-by: David Teigland <teigland@redhat.com>
diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index a53c237..d30ea8b 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -253,7 +253,10 @@
 	struct dlm_lksb		*lkb_lksb;      /* caller's status block */
 	void			(*lkb_astfn) (void *astparam);
 	void			(*lkb_bastfn) (void *astparam, int mode);
-	void			*lkb_astparam;	/* caller's ast arg */
+	union {
+		void			*lkb_astparam;	/* caller's ast arg */
+		struct dlm_user_args	*lkb_ua;
+	};
 };