msm: kgsl: Remove 'fd' dependency to get dma_buf handle

Get the dma_buf handle directly from 'vm_file' after
doing necessary checks on the file.

Change-Id: Id5eec16588d64e4e28483b32bb52d4d3d9b86b99
Signed-off-by: ravnar <quic_ravnar@quicinc.com>
Signed-off-by: Sanjay Yadav <quic_sanjyada@quicinc.com>
Signed-off-by: Abhishek Barman <quic_abarman@quicinc.com>