drm/amdkfd: add svm_bo reference for eviction fence

[why]
As part of the SVM functionality, the eviction mechanism used for
SVM_BOs is different. This mechanism uses one eviction fence per prange,
instead of one fence per kfd_process.

[how]
A svm_bo reference to amdgpu_amdkfd_fence to allow differentiate between
SVM_BO or regular BO evictions. This also include modifications to set the
reference at the fence creation call.

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>