libutils: get ride of debug trace file errors

put them as warning only...

Change-Id: Idbdddbc83833c938288da6b7a68fb3539d139538
Revert "kill the log spam for no trace file"

This reverts commit d986293794ecd837a48ab54a77916c2680a5ac3d.
Merge remote-tracking branch 'cm/cm-10.1' into cm-10.1-linaro