staging/fwserial: (coding style) remove not needed return statements

Style-only modifications to make checkpatch.pl -f a bit happier.
Fixes warning: "void function return statements are not generally useful"

Signed-off-by: Radek Dostal <rd@radekdostal.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fwserial/fwserial.c

@@ -2615,7 +2615,6 @@ cleanup:
 	if (port)
 		fwserial_release_port(port, false);
 	kfree(pkt);
-	return;
 }
 
 static void fwserial_handle_unplug_req(struct work_struct *work)
@@ -2667,7 +2666,6 @@ cleanup:
 	if (port)
 		fwserial_release_port(port, true);
 	kfree(pkt);
-	return;
 }
 
 static int fwserial_parse_mgmt_write(struct fwtty_peer *peer,