msm: camera: isp: Fix overwriting of WM data on reg_update

Bring back the shared io_buf_update data for each vfe_out,
so that when there is more than one WM per output the
reg_val_pair does not get overwritten on each iteration.
Use the wm_data io_buf_update only for RDI outputs.

Change-Id: I7c6bbf4d9658e7f6400c9f29b87b1d4af6c281cc
Signed-off-by: Kristiyan Kyosev <kkyose@codeaurora.org>