spi: tegra: remove support of legacy DMA driver based access

Remove the support code which uses the legacy APB DMA driver
for accessing the SPI FIFO.
The driver will use the dmaengine based APB DMA driver for
accessing reqding/writing to SPI FIFO.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>