Fix RealVect version of pos() for pure SoA (#3283)

The proposed changes:
- [x] fix a bug or incorrect behavior in AMReX
- [ ] add new capabilities to AMReX
- [ ] changes answers in the test suite to more than roundoff level
- [ ] are likely to significantly affect the results of downstream AMReX
users
- [ ] include documentation in the code and/or rst files, if appropriate

Src/Particle/AMReX_ParticleTile.H

@@ -385,7 +385,7 @@ struct SoAParticle : SoAParticleBase
  //functions to get positions of the particle in the SOA data
 
  AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
- RealVect pos () const & {return RealVect(AMREX_D_DECL(this->m_particle_tile_data->m_rdata[0][m_index], this->m_particle_tile_data.m_rdata[1][m_index], this->m_particle_tile_data->m_rdata[2][m_index]));}
+ RealVect pos () const & {return RealVect(AMREX_D_DECL(this->m_particle_tile_data.m_rdata[0][m_index], this->m_particle_tile_data.m_rdata[1][m_index], this->m_particle_tile_data.m_rdata[2][m_index]));}
 
  AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
  RealType& pos (int position_index) &