RISC-V: Add support for the Zvksh ISA extension

RISC-V: Add support for the Zvksh ISA extension

Zvksh is part of the vector crypto extensions.

This extension adds the following instructions:
- vsm3me.vv
- vsm3c.vi

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_multi_subset_supports): Add instruction
	class support for Zvksh.
	(riscv_multi_subset_supports_ext): Likewise.

gas/ChangeLog:

	* testsuite/gas/riscv/zvksh.d: New test.
	* testsuite/gas/riscv/zvksh.s: New test.

include/ChangeLog:

	* opcode/riscv-opc.h (MATCH_VSM3C_VI): New.
	(MASK_VSM3C_VI): New.
	(MATCH_VSM3ME_VV): New.
	(MASK_VSM3ME_VV): New.
	(DECLARE_INSN): New.
	* opcode/riscv.h (enum riscv_insn_class): Add instruction class
	support for Zvksh.

opcodes/ChangeLog:

	* riscv-opc.c: Add Zvksh instructions.

Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>