fs/reiserfs/lbalance.c: remove set but not used variables

fs/reiserfs/lbalance.c: remove set but not used variables

Fixes gcc '-Wunused-but-set-variable' warning:

fs/reiserfs/lbalance.c: In function leaf_paste_entries:
fs/reiserfs/lbalance.c:1325:9: warning: variable old_entry_num set but not used [-Wunused-but-set-variable]

Link: http://lkml.kernel.org/r/1566379929-118398-4-git-send-email-zhengbin13@huawei.com
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Reported-by: Hulk Robot <hulkci@huawei.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>