sched_ext: Fix missing SCX_EV_SUB_BYPASS_DISPATCH aggregation in scx_read_events()

sched_ext: Fix missing SCX_EV_SUB_BYPASS_DISPATCH aggregation in scx_read_events()

025b1bd41965 introduced SCX_EV_SUB_BYPASS_DISPATCH to track scheduling
of bypassed descendant tasks, and correctly increments it per-CPU and
displays it in sysfs and dump output. However, scx_read_events() which
aggregates per-CPU counters into a summary was not updated to include
this event, causing it to always read as zero in sysfs, in debug dumps,
and via the scx_bpf_events() kfunc.

Add the missing scx_agg_event() call for SCX_EV_SUB_BYPASS_DISPATCH.

Fixes: 025b1bd41965 ("sched_ext: Implement hierarchical bypass mode")
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>