[RISC-V] Avoid multiply defined insn name

When adding a ChangeLog entry for a recent change I realized the
define_insn_and_split didn't have a name.  So I added the name, but didn't
account for the iterator and thus we have the same name appearing multiple
times.

Anyway, this just adds the '*' prefix so that the name is considered for
debugging purposes only.

Pushing as obvious.

Jeff

ps.  Yes, you could argue that I should have written the ChangeLog when I wrote
the patch.

gcc/
	* config/riscv/riscv.md (seq_sne_qi): Mark name for debugging purposes
	only.