serial: tegra: remove Kconfig dependency on APB DMA controller

serial: tegra: remove Kconfig dependency on APB DMA controller

This driver runs also on SoCs without a Tegra20 APB DMA controller (e.g.
Tegra234).
Remove the Kconfig dependency on TEGRA20_APB_DMA, and remove reference to
the APB DMA controller from the Kconfig help text.

Signed-off-by: Francesco Lavra <flavra@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260303111438.2691799-1-flavra@baylibre.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>