esp32: fix WiFi stop bug in WiFi/BT coexist mode

This fix includes following changes:
1. Fix the bug that esp_restart()/esp_wifi_stop() sometimes fails in WiFi/BT coexist mode.
2. Add a timer for WiFi stop and stop WiFi forcibly once the timer expires.

diff --git a/components/esp32/lib b/components/esp32/lib
index 8c987c6b246141016674da9b33b09d4f461363f0..acc7e050c8ab15b04d2ac97085ba49823b8cd911 160000 (submodule)
--- a/components/esp32/lib
+++ b/components/esp32/lib
@@ -1 +1 @@
-Subproject commit 8c987c6b246141016674da9b33b09d4f461363f0
+Subproject commit acc7e050c8ab15b04d2ac97085ba49823b8cd911