Adapt the device package to no longer use the gpio-mcp23s08 but instead
use the pinctrl-mcp23s08-spi. In addition, the kernel configuration was
adapted so that this can be built as a module and does not have to be
integrated directly into the kernel for this target.
Signed-off-by: Florian Eckert <fe@dev.tdt.de>
f938512af6