cris: Correct gcc_assert for atomic_fetch_op pattern

cris: Correct gcc_assert for atomic_fetch_op pattern

Yet another misnumbering of operands: the asserted non-overlap
would be the only benign operands overlap.  "Suddenly" exposed
by g++.dg/cpp0x/pr81325.C when testing unrelated changes
affecting register allocation.

To wit, operands 2 and 1 are the only ones that are safe for
overlap, it's only that it doesn't seem to make much sense to
write the address of the atomic data as the atomic data.

gcc:
	* config/cris/sync.md ("cris_atomic_fetch_<atomic_op_name><mode>_1"):
	Correct gcc_assert of overlapping operands.