msm: mdp3: fix the use after free problem

currently the fdget is failed and freed in mdp3_get_img,
and again same is freed in mdp3_put_img function.
This can cause a use after free issue.

Change-Id: Ic2ad97a201d36b2bb49d3fdc93bb19ce089b6cb4
Signed-off-by: Raghavendra Ambadas <quic_c_rambad@quicinc.com>