msm: camera: flash: Add qti flash support in camera

Add support for qti flash along with updated max current DT
property. Remove support for enable/disable regulator as it
is no-op since a long time.

CRs-Fixed: 2584631
Change-Id: I3305e7b6e4d6ef34d90d38f5f25cfa5b8b817f8b
Signed-off-by: Mukund Madhusudan Atre <matre@codeaurora.org>