video: fbdev: gxfb: constify pci_device_id.

pci_device_id are not supposed to change at runtime. All functions
working with pci_device_id provided by <linux/pci.h> work with
const pci_device_id. So mark the non-const structs as const.

File size before:
text data bss dec hex filename
2643 1616 16 4275 10b3 video/fbdev/geode/gxfb_core.o

File size after adding 'const':
text data bss dec hex filename
2707 1552 16 4275 10b3 video/fbdev/geode/gxfb_core.o

Signed-off-by: Arvind Yadav <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Antonino Daplas <[e-mail]>
Cc: Maik Broemme <[e-mail]>
Cc: Florian Tobias Schandinat <[e-mail]>
Signed-off-by: Bartlomiej Zolnierkiewicz <[e-mail]>

drivers/video/fbdev/geode/gxfb_core.c

···
 	framebuffer_release(info);
 }
 
-static struct pci_device_id gxfb_id_table[] = {
+static const struct pci_device_id gxfb_id_table[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_GX_VIDEO) },
 	{ 0, }
 };