ARM: dts: msm: Use scatter-gather for SDM660 in 4.19

Update the sdm660-coresight.dtsi file to use scatter-gather
property instead of sg-enable as per the kernel 4.19 design
to ensure the Scatter gather memory type is used for ETR
instead of contiguous memory.

Change-Id: I8ae2f422f07890f0e3770676f5f7b6b6d1c45f6a