dmaengine: tegra-apb: Add missing of_dma_controller_free

The DMA controller shall be released on driver's removal.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/20200209163356.6439-15-digetx@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>