crimson/osd: fix inaccurate comment about child early-exit in get_early_config

crimson/osd: fix inaccurate comment about child early-exit in get_early_config

The comment contained a typo ("taged") and vaguely referred to "one of
the parameters" without explaining what actually happens: the child
calls exit(0) for early-exit paths such as --help and --version, and
the parent detects this by checking for a clean exit with no pipe data.

Signed-off-by: Kefu Chai <k.chai@proxmox.com>