mctpreactor: support for AST2700 USB MCTP Reactor

Add SoC mapping for AST2700 and AST2750. Add usb root
hub positions for the AST2700 and AST2750.

Tested: Tested basic mctp over usb with ast2700-evb and
ast2750-evb with RootHubPositions:
/sys/devices/platform/soc@14000000/14123000.usb

Change-Id: I95410416ee1a4a7cb1e40320a26eaa889507f2a8
Signed-off-by: Mayank Metha <mayank.metha@intel.com>

src/mctp/MCTPEndpoint.cpp

diff --git a/src/mctp/MCTPEndpoint.cpp b/src/mctp/MCTPEndpoint.cpp
index 70efb36..8a939b1 100644
--- a/src/mctp/MCTPEndpoint.cpp
+++ b/src/mctp/MCTPEndpoint.cpp
@@ -581,11 +581,24 @@
         "/sys/devices/platform/ahb/1e6a1000.usb",
         "/sys/devices/platform/ahb/1e6a3000.usb"};
 
+    // The AST2750 is the AST2700 with the same controller addresses.
+    static constexpr std::array<std::string_view, 4> ast2700RootHubs = {
+        "/sys/devices/platform/soc@10000000/12061000.usb",
+        "/sys/devices/platform/soc@10000000/12063000.usb",
+        "/sys/devices/platform/soc@14000000/14121000.usb",
+        "/sys/devices/platform/soc@14000000/14123000.usb",
+    };
+
     if (socFamily.find("AST2600") != std::string::npos ||
         socFamily.find("AST2620") != std::string::npos)
     {
         return ast2600RootHubs;
     }
+    if (socFamily.find("AST2700") != std::string::npos ||
+        socFamily.find("AST2750") != std::string::npos)
+    {
+        return ast2700RootHubs;
+    }
 
     return {};
 }