add dram bandwidth measurement & random read/write

- dram bandwidth measures time taken to memcpy between 4MB buffers
  : results devideb by screen resolutions to show screen copy per sec.
- random R/W performs 4KB access randomly for a file.
  : Each access is aligned to 4KB.
- also reduce the number of repetition in SequentialUpdate as mako
  does not complete in 30 mins

Change-Id: I7ca382f9a6e6f361278ed91447e6b8dee38a7a2f