soc/tegra: fuse: move APB DMA into Tegra20 fuse driver

The Tegra20 fuse driver is the only user of tegra_apb_readl_using_dma().
Therefore we can simply the code by incorporating the APB DMA handling into
the driver directly. tegra_apb_writel_using_dma() is dropped because there
are no users.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>