[SYS] Fix frequency units

[noelchalmers]

Description

CPU frequency displays the wrong units in occa info. The frequency is parsed from lscpu in MHz was converting to KHz, but the stringifyFrequency routine assumes it is in Hz.

[codecov]

Codecov Report

Merging #601 (0aae5fa) into main (6289743) will decrease coverage by 0.79%.
The diff coverage is 100.00%.

❗ Current head 0aae5fa differs from pull request most recent head 681760c. Consider uploading reports for the commit 681760c to get more accurate results

@@            Coverage Diff             @@
##             main     #601      +/-   ##
==========================================
- Coverage   77.33%   76.54%   -0.80%     
==========================================
  Files         264      264              
  Lines       19544    19477      -67     
==========================================
- Hits        15114    14908     -206     
- Misses       4430     4569     +139     

Impacted Files	Coverage Δ
src/occa/internal/utils/sys.cpp	80.48% <100.00%> (+2.95%)	⬆️
src/occa/internal/core/launchedKernel.cpp	0.00% <0.00%> (-100.00%)	⬇️
src/occa/internal/core/launchedDevice.cpp	0.00% <0.00%> (-79.67%)	⬇️
include/occa/types/json.tpp	45.45% <0.00%> (-24.55%)	⬇️
src/occa/internal/lang/expr/callNode.cpp	73.68% <0.00%> (-9.22%)	⬇️
include/occa/types/json.hpp	75.40% <0.00%> (-6.75%)	⬇️
src/dtype/builtins.cpp	41.66% <0.00%> (-5.56%)	⬇️
src/occa/internal/utils/string.cpp	81.33% <0.00%> (-4.00%)	⬇️
src/occa/internal/utils/styling.cpp	93.45% <0.00%> (-3.74%)	⬇️
src/occa/internal/modes/serial/registration.cpp	91.11% <0.00%> (-2.23%)	⬇️
... and 17 more