testsuite/s390: Fix risbg-ll-3.c f2_cconly test.

Instead of selecting bits 62 to (wraparound) 59 from r2 and inserting them
into r3, we select bits 60 to 62 from r3 and insert them into r2
nowadays.  Adjust the test accordingly.

gcc/testsuite/ChangeLog:

	* gcc.target/s390/risbg-ll-3.c: Change match pattern.