security: make security_file_set_fowner, f_setown and __f_setown void return

security_file_set_fowner always returns 0, so make it f_setown and
__f_setown void return functions and fix up the error handling in the
callers.

Cc: linux-security-module@vger.kernel.org
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/security/capability.c b/security/capability.c
index a74fde6..d68c57a 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -343,9 +343,9 @@
 	return 0;
 }
 
-static int cap_file_set_fowner(struct file *file)
+static void cap_file_set_fowner(struct file *file)
 {
-	return 0;
+	return;
 }
 
 static int cap_file_send_sigiotask(struct task_struct *tsk,