[vulkan] Fix coherent memory for 32-bit userspace apps

bug: 111137294

mmap64 is needed because the offset into the PCI can be quite large
(as it's 16 GB total space there).

Test: can run 3dmark sling shot extreme Vulkan edition

+ Also make sure the suballocations are aligned properly for
images/buffers, which can require alignment above nonCoherentAtomSize.
+ More debug prints

Change-Id: Ic45467a932205eaa728aea4d11626c0bb9c780ba
3 files changed