RISC-V: Fix VL operand bug in VSETVL PASS[PR110264]

This patch fixes this issue happens on both GCC-13 and GCC-14.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110264

The testcase is too big and I failed to reduce it so I didn't append
test into this patch.

This patch should not only land into GCC-14 but also should backport to GCC-13.

	PR target/110264

gcc/ChangeLog:

	* config/riscv/riscv-vsetvl.cc (insert_vsetvl): Fix bug.

(cherry picked from commit dd6e1cba)