Fixed cuFFT device missing context issue.
Execution of the cufftExecR2C and cufftExecC2R functions always resulted in a CUFFT_INTERNAL_ERROR due to a missing device context. This merge request also includes appropriate error handling
Execution of the cufftExecR2C and cufftExecC2R functions always resulted in a CUFFT_INTERNAL_ERROR due to a missing device context. This merge request also includes appropriate error handling