RISC-V: Fix the wrong encoding and operand of the XTheadFmv extension.

RISC-V: Fix the wrong encoding and operand of the XTheadFmv extension.

The description of instructions 'th.fmv.hw.x' and 'th.fmv.x.hw' of the
XTheadFmv extension in T-Head specific is incorrect, and it also has
some impact on the implementation of the binutils, so this patch
corrects this.

For details see:
https://github.com/T-head-Semi/thead-extension-spec/pull/34

gas/ChangeLog:

	* testsuite/gas/riscv/x-thead-fmv.d: Correct test.
	* testsuite/gas/riscv/x-thead-fmv.s: Likewise.

include/ChangeLog:

	* opcode/riscv-opc.h (MATCH_TH_FMV_HW_X): Correct coding.
	(MASK_TH_FMV_HW_X): Likewise.
	(MATCH_TH_FMV_X_HW): Likewise.
	(MASK_TH_FMV_X_HW): Likewise.

opcodes/ChangeLog:

	* riscv-opc.c: Correct operands.