msm: camera: cpas: Write qosgen registers when enabled

Call qosgen register update to write values into corresponding
registers.

CRs-Fixed: 2789495
Change-Id: I43eb6bc9d4cce42b78d55b4519931b15b7f6a383
Signed-off-by: Pavan Kumar Chilamkurthi <pchilamk@codeaurora.org>