build support for kernel 5.18 and above

[smCloudInTheSky]

Hi,

Found out that on kernel 5.18 and above the bump of C standard to C99 changed extern inline comportement and to keep the same behaviour I had to replace extern inline to static inline. This is a change to ieee80211.h that should handle the difference in behavior without much issue

[smCloudInTheSky]

Did saw the issue and solution on #187

[tiagogalvao]

Fixed build issues for me on latest arch kernel, thank you