Previously used “unsigned long” may lead to confusion should the code
be compiled for 64-bit machine.

This commit also removes some unused fields of the tegra_spi_data
structure as well as removes duplicated #defines.
Signed-off-by: NMichal Nazarewicz <mina86@mina86.com>
Tested-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NMark Brown <broonie@linaro.org>