Fixes the following W=1 kernel build warning(s):

fs/ubifs/replay.c:942: warning: Excess function parameter 'ref_lnum' description in 'validate_ref'
fs/ubifs/replay.c:942: warning: Excess function parameter 'ref_offs' description in 'validate_ref'

They're not in use. Remove them.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>