Don't populate the const array specialtv on the stack, instead make it
static.  Makes the object code smaller by over 1100 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
 179899	   7504	      0	 187403	  2dc0b	drivers/video/fbdev/sis/init301.o

After:
   text	   data	    bss	    dec	    hex	filename
 178720	   7568	      0	 186288	  2d7b0	drivers/video/fbdev/sis/init301.o

(gcc version 7.2.0, x86_64)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Cc: Thomas Winischhofer <thomas@winischhofer.net>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>