nilfs2: remove duplicate 'unlikely()' usage

Nested unlikely() calls, IS_ERR already uses unlikely() internally

Link: https://lkml.kernel.org/r/20240904101618.17716-1-konishi.ryusuke@gmail.com


Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>