ARM: dts: msm: Add reserved channel for MSM8998/SDM660/SDM630

Channel 511 is used for debug port on MSM8998/SDM660/SDM630
targets. Reserve the same to avoid the access from other
peripherals.

Change-Id: I928916b7d61793a07e9a3b2e1c2127a247c71730
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>