Dropbear's NSH PTY session reaps the child task with waitpid() and needs
CONFIG_SCHED_CHILD_STATUS (which depends on SCHED_HAVE_PARENT). Without it
the session fails with ECHILD right after authentication
("NSH session wait failed: Unknown error 10").
netutils/dropbear now "depends on SCHED_CHILD_STATUS" per the project's
depends-on-over-select policy (apache/nuttx-apps#3648), so enable it in the
sim and esp32c3-devkit Dropbear defconfigs (SCHED_HAVE_PARENT is already
enabled there).
Signed-off-by: Felipe Moura <moura.fmo@gmail.com>