RISC-V: Support TU for integer ternary OP[PR110964]

PR target/110964

gcc/ChangeLog:
	PR target/110964
	* config/riscv/riscv-v.cc (expand_cond_len_ternop): Add integer ternary.

gcc/testsuite/ChangeLog:
	PR target/110964
	* gcc.target/riscv/rvv/autovec/pr110964.c: New test.