ARM: dts: msm: add link clk rcg entry on sm8150

During suspend to disk we need to set link clk parent to xo during
disable. This changes adds an link_clk_rcg entry to DP device tree node.

Change-Id: I0ff6e6ee5d8380107e5e19fe3540d56ccb36ec9a
Acked-by: Poojashree Masthi <c_pmasth@qti.qualcomm.com>
Signed-off-by: Rahul Sharma <rahsha@codeaurora.org>