msm: mdss: Avoid incorrect status while parsing dsi topology

When parsing topology dtsi struct the return value gets set while
checking for qcom,split-mode. When this node and DSC construct
are not present, the rc value gets set as INVALID incorrectly.
This change prevents that scenario.

Change-Id: Id358e0d46ca5eacc75c5e7ff0064ff67f1b7e356
Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>