drm/simpledrm: Fix power domain device link validity check

We need to check if a link is non-NULL before trying to delete it.

Fixes: 61df9ca ("drm/simpledrm: Add support for multiple "power-domains"")
Signed-off-by: Thierry Reding <[email protected]>
Signed-off-by: Thomas Zimmermann <[email protected]>
Reviewed-by: Thomas Zimmermann <[email protected]>
Cc: Janne Grunau <[email protected]>
Cc: Eric Curtin <[email protected]>
Cc: Neal Gompa <[email protected]>
Cc: Sven Peter <[email protected]>
Cc: Javier Martinez Canillas <[email protected]>
Cc: [email protected]
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: thierryreding

drivers/gpu/drm/tiny/simpledrm.c

@@ -506,7 +506,7 @@ static void simpledrm_device_detach_genpd(void *res)
 		return;
 
 	for (i = sdev->pwr_dom_count - 1; i >= 0; i--) {
-		if (!sdev->pwr_dom_links[i])
+		if (sdev->pwr_dom_links[i])
 			device_link_del(sdev->pwr_dom_links[i]);
 		if (!IS_ERR_OR_NULL(sdev->pwr_dom_devs[i]))
 			dev_pm_domain_detach(sdev->pwr_dom_devs[i], true);