includecheck fix: drivers/video, vgacon.c

fix the following 'make includecheck' warning:

  drivers/video/console/vgacon.c: linux/slab.h is included more than once.
Signed-off-by: NJaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Martin Mares <mj@ucw.cz>
Cc: mchehab@infradead.org
Cc: Sam Ravnborg <sam@ravnborg.org>
LKML-Reference: <1247067624.4382.88.camel@ht.satnam>

drivers/video/console/vgacon.c

@@ -180,7 +180,6 @@ static inline void vga_set_mem_top(struct vc_data *c)
 }
 
 #ifdef CONFIG_VGACON_SOFT_SCROLLBACK
-#include <linux/slab.h>
 /* software scrollback */
 static void *vgacon_scrollback;
 static int vgacon_scrollback_tail;