msm: camera: isp: Fix checking for valid bw vote

The BW config coming from user space functions based on
usage type as single or dual. Checking the validity of bw
vote based on hw index caused bw updates to be ignored from
isp side. Fix checking for valid bw vote by falling back to
walking through all indices.

CRs-Fixed: 2669422
Change-Id: I5762fb06c8b69ade286d890146e91844fbde5ce7
Signed-off-by: Mukund Madhusudan Atre <matre@codeaurora.org>