RISC-V: Add prototypes for RISC-V Crypto built-in functions

RISC-V: Add prototypes for RISC-V Crypto built-in functions

This patch adds prototypes for RISC-V Crypto built-in functions.

gcc/ChangeLog:

	* config/riscv/riscv-builtins.cc (RISCV_FTYPE_NAME2): New.
	(RISCV_FTYPE_NAME3): New.
	(RISCV_ATYPE_QI): New.
	(RISCV_ATYPE_HI): New.
	(RISCV_FTYPE_ATYPES2): New.
	(RISCV_FTYPE_ATYPES3): New.
	* config/riscv/riscv-ftypes.def (2): New.
	(3): New.

Co-Authored-By: SiYu Wu <siyu@isrc.iscas.ac.cn>