ARM: dts: msm: Defer regulator disable for SDM670 GPU SMMU

IOMMU driver takes vote on regulator for every unmap, attach or
detach call and removes it once done.

This is an overhead if GPU is in power collapse mode and huge
number of unmap calls are pending from a given context. It would
end up in turning ON/OFF the regulator those many times.

To optimize this, do a deferred regulator disable about 80ms so that
all subsequent requests to regulator enable will be just refcounted.

Change-Id: I608dac2a6d1a731dc5d5efa55b4ef7f671f5e8f9
Signed-off-by: Rajesh Kemisetti <rajeshk@codeaurora.org>