Bump P4 tools to latest version

With support for P4Runtime multicast API

Change-Id: I6982c32187204b656a927d0f3d7f3a4b1b877e75
diff --git a/protocols/p4runtime/proto/BUCK b/protocols/p4runtime/proto/BUCK
index 2f8c07f..27a8ef6 100644
--- a/protocols/p4runtime/proto/BUCK
+++ b/protocols/p4runtime/proto/BUCK
@@ -5,7 +5,7 @@
 PROTOBUF_VER = '3.2.0'
 GRPC_VER = '1.3.1'
 
-PI_COMMIT = '59c940916b4f5b182f33b4788d8c410972eaecce'
+PI_COMMIT = '7e94b025bac6db63bc8534e5dd21a008984e38bc'
 PI_BASEURL = 'https://github.com/p4lang/PI.git'
 
 # Wondering which .proto files to build? Check p4runtime's Makefile: