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

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

This moves the iterators out from riscv.md to iterators.md
like most modern backends.
I have not moved the iterators from the other .md files yet.

OK? Build and tested on riscv64-linux-gnu and riscv32-linux-gnu.

Thanks,
Andrew Pinski

gcc/ChangeLog:

	* config/riscv/riscv.md (GPR): Move to new file.
	(P, X, BR): Likewise.
	(MOVE32, MOVE64, SHORT): Likewise.
	(HISI, SUPERQI, SUBX): Likewise.
	(ANYI, ANYF, SOFTF): Likewise.
	(size, load, default_load): Likewise.
	(softload, store, softstore): Likewise.
	(reg, fmt, ifmt, amo): Likewise.
	(UNITMODE, HALFMODE): Likewise.
	(RINT, rint_pattern, rint_rm): Likewise.
	(QUIET_COMPARISON, quiet_pattern, QUIET_PATTERN): Likewise.
	(any_extend, any_shiftrt, any_shift): Likewise.
	(any_bitwise): Likewise.
	(any_div, any_mod): Likewise.
	(any_gt, any_ge, any_lt, any_le): Likewise.
	(u, su): Likewise.
	(optab, insn): Likewise.
	* config/riscv/iterators.md: New file.