ubifs: Fix the printing type of c->big_lpt

Ubifs uses %d to print c->big_lpt, but c->big_lpt is a variable
of type unsigned int and should be printed with %u.

Signed-off-by: Chengsong Ke <kechengsong@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>