[llvm] [AMDGPU][Docs] Correct Radeon Pro 5600M ISA (PR #140041)

[Frederik Harwath via llvm-commits]

frederik-h wrote:

Compare with the output of the "Radeon GPU analyzer" which has a comprehensive list matching product names to ISAs:
```bash
$ ~/rga-2.12.0.56/rga -s bin -l | grep -C1 "Radeon Pro 5600M"
gfx1011 (RDNA)
        AMD Radeon Pro 5600M
        AMD Radeon Pro V520
```
and
```bash
$ ~/rga-2.12.0.56/rga -s bin -l | grep -C8 "Radeon RX 5600M"
        AMD Instinct(TM) MI300X
        AMD Instinct(TM) MI300XHF
gfx1010 (RDNA)
        AMD Radeon Pro 5700 XT
        AMD Radeon Pro W5700
        AMD Radeon Pro W5700X
        AMD Radeon RX 5600 OEM
        AMD Radeon RX 5600 XT
        AMD Radeon RX 5600M
        AMD Radeon RX 5700
        AMD Radeon RX 5700 XT
        AMD Radeon RX 5700 XT 50th Anniversary
        AMD Radeon RX 5700B
        AMD Radeon RX 5700M
gfx1011 (RDNA)
        AMD Radeon Pro 5600M
        AMD Radeon Pro V520
```  

https://github.com/llvm/llvm-project/pull/140041