Fix bug patching panorama benchmark

Need to create benchmark directory before patching panorama.diff.
Will also delete the directory after cleaning the git.

Meanwhile, since we are using marlin/sailfish device to do test often,
changed default frequency to 979200 to match it.

Test: Run panorama benchmark from a new repo and succeeded.
Change-Id: I1244438ef93be0d27b45b267815d619dcb86a863