ARM: dts: msm: Defer regulator disable for SDM660 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: I816156f1bdf34a2c0cb8171c2ca1df6b3ae8fe72
Signed-off-by: Rajesh Kemisetti <rajeshk@codeaurora.org>