drivers/spi: Always selecet HAS_DTS_SPI once SPI is enabled

All drivers require DTS for their primary SPI settings.

Removing SPI_[0-9]_NAME config option added some more samples changes.
Usage of these options there was anyway not relevant.

Fixes #11064

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>