msm: npu: clean up debug messages

This change is to reduce npu driver debug messages When debug
mode is enabled. IPC queue debug function is also modified to
only dump valid contents.

Change-Id: I7c0d9b5737a6d52a62801fddddad7c8c34b23be7
Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>