change solib-frv to use entry_point_address_query

This is just a minor cleanup in advance of some other changes, that
modifies solib-frv.c to use entry_point_address_query.  I don't have a
good way to test this but I think it is obviously correct.

2014-01-15  Tom Tromey  <tromey@redhat.com>

	* solib-frv.c (enable_break): Use entry_point_address_query.