[sairedis]: update sairedis submodule head (#956)

yxieca · Shuotian Cheng · commit 3cbc080f7b3f · 2017-09-15T11:15:04.000-07:00
This submodule update includes the deadlock fixes.
diff --git a/src/sonic-sairedis b/src/sonic-sairedis
@@ -1 +1 @@
-Subproject commit 7e70b4d63020fc9ea1aa009c264e4effab7bcda0
+Subproject commit 4d7deba9354c922d18d75325dcd4255f4096560f
