Incorrect docstrings

```
/vsts/agent/_work/2/s/third-party/pcm/src/cpucounters.h:483:10: error: duplicated command '\brief' [-Werror,-Wdocumentation]
//! \brief metrics metric set (see the ServerUncoreMemoryMetrics enum)
~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/vsts/agent/_work/2/s/third-party/pcm/src/cpucounters.h:480:10: note: previous command '\brief' here
//! \brief Program memory counters (disables programming performance counters)
~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/vsts/agent/_work/2/s/third-party/pcm/src/cpucounters.h:1183:14: error: '\returns' command used in a comment that is attached to a function returning void [-Werror,-Wdocumentation]
* \returns nothing
~^~~~~~~~~~~~~~~
/vsts/agent/_work/2/s/third-party/pcm/src/cpucounters.h:1191:14: error: '\returns' command used in a comment that is attached to a function returning void [-Werror,-Wdocumentation]
* \returns nothing
~^~~~~~~~~~~~~~~
/vsts/agent/_work/2/s/third-party/pcm/src/cpucounters.h:1766:10: error: '\return' command used in a comment that is attached to a function returning void [-Werror,-Wdocumentation]
\return acceltype
~^~~~~~~~~~~~~~~~
/vsts/agent/_work/2/s/third-party/pcm/src/cpucounters.h:1776:10: error: '\return' command used in a comment that is attached to a function returning void [-Werror,-Wdocumentation]
\return number of counters
~^~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /vsts/agent/_work/2/s/third-party/pcm/src/cpucounters.h/vsts/agent/_work/2/s/knp/devices-library/impl/cpu.cpp:13:
/vsts/agent/_work/2/s/third-party/pcm/src/cpucounters.h:483:10: error: duplicated command '\brief' [-Werror,-Wdocumentation]
```

Probably CLang build with -Werror,-Wdocumentation will show this problem?