usb: dwc3-msm: Remove DOMAIN_ATTR_UPSTREAM_IOVA_ALLOCATOR

The DOMAIN_ATTR_UPSTREAM_IOVA_ALLOCATOR iommu domain attribute
is no long present as the default allocation behavior aligns
with the upstream based dma_ops. Thus remove it.

Change-Id: I126480c51fa86bb1b47eecbcad727148a3c8ebd7
Signed-off-by: Jack Pham <jackp@codeaurora.org>