This research was supported in part through computational resources provided by the Kathmandu University Supercomputer Centre, which was established with equipment donated by CERN. Shambhu is very grateful to the Supercomputer Center (Kathmandu University) for providing high-performance computing facilities during the research work. A fruitful discussion with Dr. Rajendra Adhikari and Keshav Sigdel (Kathmandu University) is acknowledged.