ARM: dts: msm: disable kgsl smmu ATOS for sdm670

Commit 14b51d92 ("ARM: dts: msm: remove non essential clocks with kgsl
iommu for sdm670") removes gcc_ddrss_gpu_axi_clk and gpu_cc_cx_gmu_clk from
kgsl SMMU DT clk list. Without these clock enabled smmu ATOS setup will
fail. ATOS is a debug functionality, hence it's safe to disable on kgsl
smmu for sdm670.

Change-Id: I64b09c7c0a4539ac9c8145120123979fdb22b578
Signed-off-by: Prakash Gupta <guptap@codeaurora.org>