Implement support for FS_IOC_SETFSLABEL ioctl to write filesystem label.

Link: https://lkml.kernel.org/r/20240815074408.5550-5-konishi.ryusuke@gmail.comSigned-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>