ksmbd: server: avoid busy polling in accept loop

ksmbd: server: avoid busy polling in accept loop

The ksmbd listener thread was using busy waiting on a listening socket by
calling kernel_accept() with SOCK_NONBLOCK and retrying every 100ms on
-EAGAIN. Since this thread is dedicated to accepting new connections,
there is no need for non-blocking mode.

Switch to a blocking accept() call instead, allowing the thread to sleep
until a new connection arrives. This avoids unnecessary wakeups and CPU
usage. During teardown, call shutdown() on the listening socket so that
accept() returns -EINVAL and the thread exits cleanly.

The socket release mutex is redundant because kthread_stop() blocks until
the listener thread returns, guaranteeing safe teardown ordering.

Also remove sk_rcvtimeo and sk_sndtimeo assignments, which only caused
accept() to return -EAGAIN prematurely.

Signed-off-by: Qingfang Deng <dqfext@gmail.com>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>