dm-bufio.c: there's no need to include linux/version.h

As 'make versioncheck' points out, drivers/md/dm-bufio.c has no need to include
linux/version.h, so this patch removes the unneeded include.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/md/dm-bufio.c

@@ -12,7 +12,6 @@
 #include <linux/dm-io.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
-#include <linux/version.h>
 #include <linux/shrinker.h>
 #include <linux/module.h>