reactor: clarify read_request_base_count comment
reactor: clarify read_request_base_count comment

It seems like the comment was based on read_request_base_count being
defined as 100, yet it's defined as 128 so the comment doesan't make
sense.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

scylladb/seastar,scylladb/seastar,cloudius-systems/seastar,syuu1228/seastar,cloudius-systems/seastar,dreamsxin/seastar,scylladb/seastar,cloudius-systems/seastar,avikivity/seastar,dreamsxin/seastar,syuu1228/seastar,avikivity/seastar,avikivity/seastar,dreamsxin/seastar,syuu1228/seastar