tools: add hmm gup tests for device coherent type

tools: add hmm gup tests for device coherent type

The intention is to test hmm device coherent type under different get user
pages paths.  Also, test gup with FOLL_LONGTERM flag set in device
coherent pages.  These pages should get migrated back to system memory.

Link: https://lkml.kernel.org/r/20220531200041.24904-13-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>