Fix PPC insn names and psq displacement

[riptl]

Fixes bug where PowerPC psq_l, psq_lu, psq_st, psq_stu operands get printed as unsigned operands (should be signed).

Fixes bug where almost all instruction names are wrong in PowerPC due to PPCMappingInsnName.c table getting out of sync with ppc.h.

Adds ppc32ps and ppc32beps cstool modes.

Avoid setting PowerPC branch hint on signed disp.

---

Before:

% ./cstool/cstool -d --help ppc32beps 'f3ec0ff8'
 0  f3 ec 0f f8  psq_st f31, 0xff8(r12), 0, 0
        ID: 1694 (xvtstdcdp)
        op_count: 4
                operands[0].type: REG = f31
                operands[1].type: MEM
                        operands[1].mem.base: REG = r12
                        operands[1].mem.disp: 0xff8
                operands[2].type: IMM = 0x0
                operands[3].type: IMM = 0x0

After:

% ./cstool/cstool -d --help ppc32beps 'f3ec0ff8'                                            
 0  f3 ec 0f f8  psq_st f31, -8(r12), 0, 0
        ID: 1694 (psq_st)
        op_count: 4
                operands[0].type: REG = f31
                operands[1].type: MEM
                        operands[1].mem.base: REG = r12
                        operands[1].mem.disp: 0xfffffff8
                operands[2].type: IMM = 0x0
                operands[3].type: IMM = 0x0

cc @kabeor

[kabeor]

plz add opcode test at https://github.com/capstone-engine/capstone/blob/next/suite/cstest/issues.cs

[kabeor]

Great! Merged.

[aquynh]

where is this fix from: by yourself, or from upstream llvm?

[riptl]

@aquynh Myself because LLVM doesn't support the paired-singles extension