msm: camera: Reserve composite 2/3 for dual VFE

When dual vfe is used, both composite irq 2 & 3
are needed to trigger camss microcontroller to
update certain vfe registers. This change adds the
support to configure the irq mask based on VFE
output path. Composite 2 is used to trigger preview
path done irq and Composite 3 is used to trigger
encoder path done irq. This change also fixes the
problem where composite mask info is clear before
clearing hardware registers.

Change-Id: Ifacec4874883c51ae5b1954d64e501536b4d8e8d
Signed-off-by: Kevin Chan <ktchan@codeaurora.org>