benchmark

[sysinfo] Fix CPU Frequency reading on AMD Ryzen CPU's (#1117)

Currently, i get:
```
Run on (32 X 7326.56 MHz CPU s)
CPU Caches:
  L1 Data 32 KiB (x16)
  L1 Instruction 32 KiB (x16)
  L2 Unified 512 KiB (x16)
  L3 Unified 32768 KiB (x2)
```
which seems mostly right, except that the frequency is rather bogus.
Yes, i guess the CPU could theoretically achieve that,
but i have 3.6GHz configured, and scaling disabled.
So we clearly read the wrong thing.

With this fix, i now get the expected
```
Run on (32 X 3598.53 MHz CPU s)
CPU Caches:
  L1 Data 32 KiB (x16)
  L1 Instruction 32 KiB (x16)
  L2 Unified 512 KiB (x16)
  L3 Unified 32768 KiB (x2)
```