Fix sock_exceed_buf_limit not being triggered in __sk_mem_raise_allocated

Fix sock_exceed_buf_limit not being triggered in __sk_mem_raise_allocated

When a process under memory pressure is not part of any cgroup and
the charged flag is false, trace_sock_exceed_buf_limit was not called
as expected.

This regression was introduced by commit 2def8ff3fdb6 ("sock:
Code cleanup on __sk_mem_raise_allocated()"). The fix changes the
default value of charged to true while preserving existing logic.

Fixes: 2def8ff3fdb6 ("sock: Code cleanup on __sk_mem_raise_allocated()")
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Signed-off-by: Tengteng Yang <yangtengteng@bytedance.com>
Link: https://patch.msgid.link/20250527030419.67693-1-yangtengteng@bytedance.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>