gpio: qixis-fpga: add missing module description

gpio: qixis-fpga: add missing module description

A kernel module must have a license and should have a description. Add
missing MODULE_LICENSE(), MODULE_DESCRIPTION() and throw in a
MODULE_AUTHOR() for good measure.

This fixes the following build issues:

ERROR: modpost: missing MODULE_LICENSE() in drivers/gpio/gpio-qixis-fpga.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpio/gpio-qixis-fpga.o

Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/all/aPJW8HIke5pj3doX@sirena.org.uk/
Fixes: e88500247dc3 ("gpio: add QIXIS FPGA GPIO controller")
Link: https://lore.kernel.org/r/20251020072028.21423-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>