msm: vidc: Update DCVS thresholds

DCVS Min Threshold should be FW Min count. Switch to Load_Norm
only when buffers are equally distributed between FW and Client.
This reduces clock transitions and increases residency in
Load_Low and Load_High.

CRs-Fixed: 2502809
Change-Id: I4896fd8fdffb44b546c6df3321e0155ee4a18dcb
Signed-off-by: Chinmay Sawarkar <chinmays@codeaurora.org>