[RISCV] Move iterators from bitmanip.md to iterators.md

[RISCV] Move iterators from bitmanip.md to iterators.md

Just like the previous patch this move all of the iterators
of bitmanip.md to iterators.md.  All modern backends put the
iterators in iterators.md for easier access.

OK? Built and tested for riscv32-linux-gnu with --with-arch=rv32imafdc_zba_zbb_zbc_zbs.

Thanks,
Andrew Pinski

gcc/ChangeLog:

	* config/riscv/bitmanip.md
	(bitmanip_bitwise, bitmanip_minmax, clz_ctz_pcna,
	tbitmanip_optab, bitmanip_insn, shiftm1): Move to ...
	* config/riscv/iterators.md: Here.