msm: 8x60: Add function to reserve memory from device tree

Memory reservations for memory pools or using memblock remove
must happen early at bootup. Add a function at early boot to
walk the flattened device tree and extract memory reservation
information from appropriate bindings in device tree. To ensure
that the memory is only reserved when a driver is enabled,
drivers must put EXPORT_COMPAT(<compat string>) in the driver
as well as adding the binding to the device tree. More
documentation is available in
Documentation/devicetree/bindings/arm/msm/memory-reserve.txt
gpu: ion: Add support for device tree
msm: kgsl: Fix the address translation ranges for GPU IOMMU
Set the address translation to happen via ttbr0 for GPU IOMMU till
address 0x80000000 instead of 0x40000000. Also, adjust the size of
virtual pool so that it does not allocate an address greater
than 0x80000000.