main: Fix some "may be used uninitialized" warnings
/usr/include/glib-2.0/glib/gmacros.h: In function ‘get_drm_cards’:
/usr/include/glib-2.0/glib/gmacros.h:1212:17: warning: ‘parent’ may be used uninitialized [-Wmaybe-uninitialized]
1212 | { if (_ptr) (cleanup) ((ParentName *) _ptr); } \
| ^
../src/switcheroo-control.c:367:32: note: ‘parent’ was declared here
367 | g_autoptr(GUdevDevice) parent;
| ^~~~~~
/usr/include/glib-2.0/glib/gmacros.h:1212:17: warning: ‘parent’ may be used uninitialized [-Wmaybe-uninitialized]
1212 | { if (_ptr) (cleanup) ((ParentName *) _ptr); } \
| ^
../src/switcheroo-control.c:339:32: note: ‘parent’ was declared here
339 | g_autoptr(GUdevDevice) parent;
| ^~~~~~
/usr/include/glib-2.0/glib/gmacros.h:1212:17: warning: ‘parent’ may be used uninitialized [-Wmaybe-uninitialized]
1212 | { if (_ptr) (cleanup) ((ParentName *) _ptr); } \
| ^
../src/switcheroo-control.c:289:32: note: ‘parent’ was declared here
289 | g_autoptr(GUdevDevice) parent;
| ^~~~~~