drm/amdgpu: Optimization of AMDGPU_BO_LIST_OP_CREATE (v2)

v2: Remove duplication of zeroing of bo list (Christian König)
    Move idr_alloc function to end of ioctl (Christian König)
    Call kfree bo_list when amdgpu_bo_list_set return error.
    Combine the previous two patches into this patch.
    Add amdgpu_bo_list_set function prototype.

Signed-off-by: Alex Xie <AlexBin.Xie@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>