ARM: dts: msm: add rgb interface device node on qcs405

Add mdss_rgb device node to configure rgb interface and
mdss_rgb_spi device node to configure spi controller to
access rgb panel.

Change-Id: I4f83aa6e18ddd9c6ad61f515b67d3b5d434f01c2
Signed-off-by: Narender Ankam <nankam@codeaurora.org>