nilfs2: convert segment buffer to use kmap_local

In the segment buffer code used for log writing, a CRC calculation routine
uses the deprecated kmap_atomic(), so convert it to use kmap_local.

Link: https://lkml.kernel.org/r/20240122140202.6950-3-konishi.ryusuke@gmail.com


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