soc: qcom: hgsl: fix potential use after free

A malicous user can close the fd after dma_buf_fd, then there
will be a use after free issue due to later's get_dma_buf, fix
it by installing fd after get_dma_buf.

Change-Id: Iffca7c0eb1cc58a6a52a7100e55a639c75ff0a62
Signed-off-by: Hui Li <quic_hul@quicinc.com>