[media] staging/media/solo6x10: Use PTR_RET rather than if(IS_ERR(...)) + PTR_ERR

Found with coccicheck.
The semantic patch that makes this change is available
in scripts/coccinelle/api/ptr_ret.cocci.
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/media/solo6x10/v4l2.c

@@ -415,10 +415,7 @@ static int solo_start_thread(struct solo_filehandle *fh)
 {
 	fh->kthread = kthread_run(solo_thread, fh, SOLO6X10_NAME "_disp");
 
-	if (IS_ERR(fh->kthread))
-		return PTR_ERR(fh->kthread);
-
-	return 0;
+	return PTR_RET(fh->kthread);
 }
 
 static void solo_stop_thread(struct solo_filehandle *fh)