msm: npu: Support MSM_NPU_GET_PROP and update DCVS mode

This change is to add new IOCTL command MSM_NPU_GET_PROP to
allow user to retrieve fw properties. It also updates DCVS
handling when it's enabled.

Change-Id: I82061d840824d8ee2b62abe4cc30137b2991b3bf
Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>