x86: UD0 (`0F FF xx`) instruction disassembled incorrectly

[jxors]

Work environment

Questions	Answers
System Capstone runs on OS/arch/bits	Ubuntu 24.04 (x86 64-bit)
Capstone module affected	x86
Source of Capstone	git clone
Version/git commit	8872be6

Instruction bytes giving faulty results

0x0F,0xFF,0x00

Expected results

It should be:

0f ff 00                                         ud0

But is:

0f ff                                            ud0

Capstone does not decode a ModRM byte at the end of the instruction, and accepts 0F FF as the full instruction.

Steps to get the wrong result

With cstool:

cstool -d x64 0fff00

Additional Logs, screenshots, source code, configuration dump, ...

I suspect this may be caused by an incorrect entry in the automatically generated files from LLVM's TableGen.
I am happy to give fixing this a try, but I have not worked with LLVM before and I am not sure I have the necessary skills to fix this.