[mclag] Use port-isolation feature for Marvell platforms. (sonic-net#…

…3151)

What I did
MCLAG: Use port-isolation functionality instead of ACLs for Marvell platforms
Why I did it
Minimize the impact of ACL scaling in marvell platforms.

mclagsyncd/mclaglink.cpp

@@ -192,7 +192,8 @@ void MclagLink::setPortIsolate(char *msg)
     static const unordered_set<string> supported {
         BRCM_PLATFORM_SUBSTRING,
         BFN_PLATFORM_SUBSTRING,
-        CTC_PLATFORM_SUBSTRING
+        CTC_PLATFORM_SUBSTRING,
+        MRVL_PLATFORM_SUBSTRING
     };
 
     const char *platform = getenv("platform");

mclagsyncd/mclaglink.h

@@ -54,6 +54,7 @@
 #define BRCM_PLATFORM_SUBSTRING "broadcom"
 #define BFN_PLATFORM_SUBSTRING  "barefoot"
 #define CTC_PLATFORM_SUBSTRING  "centec"
+#define MRVL_PLATFORM_SUBSTRING "marvell"
 
 using namespace std;