[wpilib] Improve PDP comments (NFC) (#3427)

Also remove HAL doxygen comments from sources;
these functions already had more descriptive comments in their
corresponding headers.

wpilibc/src/main/native/cpp/PowerDistributionPanel.cpp

@@ -18,9 +18,6 @@ using namespace frc;
 
 PowerDistributionPanel::PowerDistributionPanel() : PowerDistributionPanel(0) {}
 
-/**
- * Initialize the PDP.
- */
 PowerDistributionPanel::PowerDistributionPanel(int module) : m_module(module) {
   int32_t status = 0;
   m_handle = HAL_InitializePDP(module, &status);