msm: vidc: Amend DCVS condition

Amend DCVS condition as follows

    - Enable it for 1 encoder and 1 decoder concurent sessions.
    - Remove low power dependency for encoder.
    - Extra buffer count based on DCVS.

Also derive clock based on encoder load.

This change also reverts change @ commit b0b1581f
("msm: vidc: Use Dcvs only when there is no resolution change")

CRs-Fixed: 1050357
Change-Id: I3a15f830e52ee89ea81d0e450b68ef13970d0363
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>