Comment/Remove Unused Parameters (#749)

Use the `clang-tidy` pass `misc-unused-parameters` to remove unused
parameter warnings.

https://clang.llvm.org/extra/clang-tidy/checks/misc-unused-parameters.html)

Committed as generic user so git does not credit the many lines to me:
```bash
GIT_AUTHOR_NAME="Tools" GIT_AUTHOR_EMAIL="warpx@lbl.gov"  \
  git commit
```

1 files changed, 2 insertions, 2 deletions

diff --git a/Source/Particles/PhotonParticleContainer.cpp b/Source/Particles/PhotonParticleContainer.cpp
index 0f0eb2284..67efb127f 100644
--- a/Source/Particles/PhotonParticleContainer.cpp
+++ b/Source/Particles/PhotonParticleContainer.cpp
@@ -56,7 +56,7 @@ void PhotonParticleContainer::InitData()
 }
 
 void
-PhotonParticleContainer::PushPX(WarpXParIter& pti, Real dt, DtType a_dt_type)
+PhotonParticleContainer::PushPX(WarpXParIter& pti, Real dt, DtType /*a_dt_type*/)
 {
 
     // This wraps the momentum and position advance so that inheritors can modify the call.
@@ -101,7 +101,7 @@ PhotonParticleContainer::Evolve (int lev,
                                  MultiFab* rho, MultiFab* crho,
                                  const MultiFab* cEx, const MultiFab* cEy, const MultiFab* cEz,
                                  const MultiFab* cBx, const MultiFab* cBy, const MultiFab* cBz,
-                                 Real t, Real dt, DtType a_dt_type)
+                                 Real t, Real dt, DtType /*a_dt_type*/)
 {
     // This does gather, push and depose.
     // Push and depose have been re-written for photon,