dsp-kernel: Free memory for GIDs after privileged process check

Currently, memory allocated for storing GIDs is kept for the entire
process lifetime, which is unnecessary. GIDs are only required to
check if a process is privileged. Free the memory for GIDs after
the privileged process check.

Change-Id: Ie4ee21b1b00fb5ba1fda04bd4f194a2595c693f8
Signed-off-by: Anandu Krishnan E <quic_anane@quicinc.com>