staging: xgifb: make const array static to shink object code size

Don't populate const array LCDARefreshIndex on the stack, instead
make it static.  Makes the object code smaller by 340 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
  84949	  12336	      0	  97285	  17c05	drivers/staging/xgifb/vb_setmode.o

After:
   text	   data	    bss	    dec	    hex	filename
  84506	  12432	      0	  96938	  17aaa	drivers/staging/xgifb/vb_setmode.o

(gcc version 7.2.0 x86_64)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/xgifb/vb_setmode.c

@@ -5046,7 +5046,7 @@ unsigned short XGI_GetRatePtrCRT2(struct xgi_hw_device_info *pXGIHWDE,
 				  unsigned short ModeIdIndex,
 				  struct vb_device_info *pVBInfo)
 {
-	const u8 LCDARefreshIndex[] = {
+	static const u8 LCDARefreshIndex[] = {
 		0x00, 0x00, 0x03, 0x01, 0x01, 0x01, 0x01, 0x00 };
 
 	unsigned short RefreshRateTableIndex, i, index, temp;