drm/amdgpu: increase hmm range get pages timeout

When application tries to allocate all system memory and cause memory
to swap out. Needs more time for hmm_range_fault to validate the
remaining page for allocation. To be safe, increase timeout value to
1 second for 64MB range.

Signed-off-by: James Zhu <James.Zhu@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>