fbdev/atafb: Remove unused extern variables

Remove 6 unused extern variables to reduce confusion. It is worth
mentioning that lib/fonts/font_8x8.c and lib/fonts/font_8x16.c also
declare `fontdata_8x8` and `fontdata_8x16` respectively, and this file
has nothing to do with them.

Signed-off-by: Peilin Ye <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/cb5[e-mail]
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/fbdev/atafb.c

···
 
 static int inverse;
 
-extern int fontheight_8x8;
-extern int fontwidth_8x8;
-extern unsigned char fontdata_8x8[];
-
-extern int fontheight_8x16;
-extern int fontwidth_8x16;
-extern unsigned char fontdata_8x16[];
-
 /*
  * struct fb_ops {
  *	* open/release and usage marking