[socket] Add BSD socket support for nRF52 (#16699)

Co-authored-by: tomaszduda23 <tomaszduda23@gmail.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>

esphome/components/socket/bsd_sockets_impl.cpp

@@ -22,11 +22,13 @@ BSDSocketImpl::BSDSocketImpl(int fd, bool monitor_loop) {
   if (flags >= 0)
     ::fcntl(this->fd_, F_SETFD, flags | FD_CLOEXEC);
 #endif
+  // Guard structure matches socket_ready_fd(): non-HOST platforms (nRF52/OpenThread)
+  // do not register fds with the esphome select loop, so monitor_loop is a no-op there.
   if (!monitor_loop)
     return;
 #ifdef USE_LWIP_FAST_SELECT
   this->cached_sock_ = hook_fd_for_fast_select(this->fd_);
-#else
+#elif defined(USE_HOST)
   this->loop_monitored_ = wake_register_fd(this->fd_);
 #endif
 }
@@ -45,7 +47,7 @@ int BSDSocketImpl::close() {
   // touch an unrelated socket's pcb. No per-socket callback unhook is needed —
   // all LwIP sockets share the same static event_callback.
   this->cached_sock_ = nullptr;
-#else
+#elif defined(USE_HOST)
   if (this->loop_monitored_) {
     wake_unregister_fd(this->fd_);
   }