CLEANUP: connection: properly name the CO_ER_SSL_FATAL enum entry

CLEANUP: connection: properly name the CO_ER_SSL_FATAL enum entry

It was the only one prefixed with "CO_ERR_", making it harder to batch
process and to look up. It was added in 2.5 by commit 61944f7a73 ("MINOR:
ssl: Set connection error code in case of SSL read or write fatal failure")
so it can be backported as far as 2.6 if needed to help integrate other
patches.

(cherry picked from commit 393957908bf492ff6660fba239106f0da7988fe8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>