ARM: dts: msm: Remove buffer partition and idle indicator

Video driver do not rely on IDLE message from firmware.
The change disable the same.
It add the required tag to load the Venus firmware by name.

Change-Id: I681f6bfa4108f15d1b91eb91fbee121c1318f7ca
Signed-off-by: Vikash Garodia <vgarodia@codeaurora.org>