fat: remove redundant sys_tz declaration

sys_tz is already declared extern struct in include/linux/time.h

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/fat/misc.c

@@ -164,8 +164,6 @@ int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
 	return 0;
 }
 
-extern struct timezone sys_tz;
-
 /*
  * The epoch of FAT timestamp is 1980.
  *     :  bits :     value