drm/amdgpu: update the functions to use amdgpu version of hmm

drm/amdgpu: update the functions to use amdgpu version of hmm

At times we need a bo reference for hmm and for that add
a new struct amdgpu_hmm_range which will hold an optional
bo member and hmm_range.

Use amdgpu_hmm_range instead of hmm_range and let the bo
as an optional argument for the caller if they want to
the bo reference to be taken or they want to handle that
explicitly.

Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>