pvr_mmu_unmap
int pvr_mmu_unmap(struct pvr_mmu_op_context *op_ctx, u64 device_addr, u64 size);
int err = pvr_mmu_unmap(ctx->mmu_op_ctx, op->unmap.va->va.addr,
err = pvr_mmu_unmap(ctx->mmu_op_ctx, va_start, va_range);