CRIS: Correct "T" to define_memory_constraint, not define_constraint

This patch has no effect on builds using reload of libgcc, newlib libc, my
own at-a-glance-testsuite and coremark.  That somewhat surprisingly
also goes for LRA builds, even with all CRIS reload_in_progress
augmented to include lra_in_progress.  I just noticed it when checking
because another port had a similar fix, where it mattered for LRA.

	* config/cris/constraints.md ("T"): Correct to
	define_memory_constraint.