msm: dsi: Read dcs-cmd-by-left property for all display destinations

After 'commit 8635960b
("msm: mdss: refactor MDSS DSI driver")' there is no longer
the need to identify display destination types while reading
the dcs-cmd-by-left property.

Crs-Fixed: 874616
Change-Id: I765c810da1eb4f4bcd5e2c4e585ee7021a6274ee
Signed-off-by: Siddhartha Agrawal <agrawals@codeaurora.org>