rocket: fix compiler warning on rocket_pci_ids

Annotate rocket_pci_ids as '__used' to fix following warning:

  CC      drivers/char/rocket.o
drivers/char/rocket.c:1767: warning: ‘rocket_pci_ids’ defined but not used
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/char/rocket.c

@@ -1764,7 +1764,7 @@ static void rp_flush_buffer(struct tty_struct *tty)
 
 #ifdef CONFIG_PCI
 
-static struct pci_device_id __devinitdata rocket_pci_ids[] = {
+static struct pci_device_id __devinitdata __used rocket_pci_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_RP, PCI_ANY_ID) },
 	{ }
 };