msm: camera: common: Define debugflag to allocate usecase info

Define debug flag to allocate usecase info for debug purpose.
This flag can be used to get usecase buffer index.

CRs-Fixed: 2707314
Change-Id: Iffacdb48f77ec6907b8070d4c19eb1c56be30f14
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>