svm range structure stores the range start address, size, attributes,
flags, prefetch location and gpu bitmap which indicates which GPU this
range maps to. Same virtual address is shared by CPU and GPUs.

Process has svm range list which uses both interval tree and list to
store all svm ranges registered by the process. Interval tree is used by
GPU vm fault handler and CPU page fault handler to get svm range
structure from the specific address. List is used to scan all ranges in
eviction restore work.

No overlap range interval [start, last] exist in svms object interval
tree. If process registers new range which has overlap with old range,
the old range split into 2 ranges depending on the overlap happens at
head or tail part of old range.

Apply attributes preferred location, prefetch location, mapping flags,
migration granularity to svm range, store mapping gpu index into bitmap.
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>