x86/insn: Fix CTEST instruction decoding

insn_decoder_test found a problem with decoding APX CTEST instructions:

	Found an x86 instruction decoder bug, please report this.
	ffffffff810021df	62 54 94 05 85 ff    	ctestneq
	objdump says 6 bytes, but insn_get_length() says 5

It happens because x86-opcode-map.txt doesn't specify arguments for the
instruction and the decoder doesn't expect to see ModRM byte.

Fixes: 690ca3a3 ("x86/insn: Add support for APX EVEX instructions to the opcode map")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org # v6.10+
Link: https://lore.kernel.org/r/20250423065815.2003231-1-kirill.shutemov@linux.intel.com