component/bt : fix interrupt slow reaction cause assert(interrupt wdt)

Some application lock interrupt(portENTER_CRITICAL) too long time,
it will cause bluetooth cannot react interrupt in time, then t will
cause some assert, assert info following:
1. ld_acl.c 1900
2. ld_fm.c 340
3. other assert reference to this.

diff --git a/components/bt/lib b/components/bt/lib
index 4e9fdabfebc241f42be895c24e1790972e47d7ff..b76cf6aa307acca2bf3634f2534c84b89f60a054 160000 (submodule)
--- a/components/bt/lib
+++ b/components/bt/lib
@@ -1 +1 @@
-Subproject commit 4e9fdabfebc241f42be895c24e1790972e47d7ff
+Subproject commit b76cf6aa307acca2bf3634f2534c84b89f60a054