ARM: dts: msm: add reserved plane node on msm8996 auto boards

Early RVC will enable vig0 layer if it's on in bootloader. So to
meet the purpose LK and kernel can access display hardware at the
same time, this pipe should be reserved in LK and set to not available
to others before RVC exits.

CRs-Fixed: 2225630
Change-Id: I1398db5750c01523e4b755fb4744a6fc976ee8da
Signed-off-by: Guchun Chen <guchunc@codeaurora.org>