Adds the drv8424 stepper driver to the build_all/stepper test and the
stepper_api test. The later test is also modified to ensure compatibility.
Signed-off-by: Jan Behrens <jan.behrens@navimatix.de>
This commit fixes minor copyright issues and corrects the compatible of
gpio-stepper with the vendor name as zephyr
Signed-off-by: Jilay Pandya <jilay.pandya@outlook.com>
