[hal] Rename PowerDistributionPanel to PowerDistribution (#3466)

Makes HAL more generic for the PDP, to enable the Rev PDH in the future.

wpilibcExamples/src/main/cpp/examples/CANPDP/cpp/Robot.cpp

@@ -2,7 +2,7 @@
 // Open Source Software; you can modify and/or share it under the terms of
 // the WPILib BSD license file in the root directory of this project.
 
-#include <frc/PowerDistributionPanel.h>
+#include <frc/PowerDistribution.h>
 #include <frc/TimedRobot.h>
 #include <frc/smartdashboard/SmartDashboard.h>
 
@@ -31,7 +31,7 @@ class Robot : public frc::TimedRobot {
 
  private:
   // Object for dealing with the Power Distribution Panel (PDP).
-  frc::PowerDistributionPanel m_pdp;
+  frc::PowerDistribution m_pdp;
 };
 
 #ifndef RUNNING_FRC_TESTS