msm: vidc: adjust computed frame rate to standard fps.

- If frame rate is 30.x frame rate being rounded to 31,
  which is causing load calculation go to higher.
- If computed fps is around standard frame rate value,
  adjust it to standard fps.

Change-Id: I589886785898c8f6c0410c4e934036cd34398b36
CRs-Fixed: 491664
Signed-off-by: Srinu Gorle <sgorle@codeaurora.org>