added physics/turbulence.F90acc kernel instruction in vdif_cd and vdif_k...
added physics/turbulence.F90acc kernel instruction in vdif_cd and vdif_k subroutine + merged 2 acc kernels
added physics/turbulence.F90acc kernel instruction in vdif_cd and vdif_k subroutine + merged 2 acc kernels