Fix External CPU API

Match https://github.com/renode/renode-infrastructure/commit/03eb1abf

Also fix PerformanceInMips data type warning

Bypass-Presubmit-Reason: test_nexus_boot_robot test broken at ToT

Change-Id: Id3c5f273bd206e0f85cfc71a16218ae862778d03

shodan_infrastructure/KelvinCPU.cs

diff --git a/shodan_infrastructure/KelvinCPU.cs b/shodan_infrastructure/KelvinCPU.cs
index 385ec1f..299bdbc 100644
--- a/shodan_infrastructure/KelvinCPU.cs
+++ b/shodan_infrastructure/KelvinCPU.cs
@@ -147,7 +147,7 @@
         }
 
         // No-op public API to match RiscVCPU
-        public Int32 PerformanceInMips { get; set; }
+        public uint PerformanceInMips { get; set; }
 
         public override string Architecture { get { return "kelvin"; } }
 
@@ -211,7 +211,7 @@
             }
         }
 
-        protected override ExecutionResult ExecuteInstructions(
+        public override ExecutionResult ExecuteInstructions(
             ulong numberOfInstructionsToExecute,
             out ulong numberOfExecutedInstructions)
         {

shodan_infrastructure/MpactCheriotCPU.cs

diff --git a/shodan_infrastructure/MpactCheriotCPU.cs b/shodan_infrastructure/MpactCheriotCPU.cs
index b115bad..3c5960e 100644
--- a/shodan_infrastructure/MpactCheriotCPU.cs
+++ b/shodan_infrastructure/MpactCheriotCPU.cs
@@ -262,7 +262,7 @@
         }
     }
 
-    protected override ExecutionResult ExecuteInstructions(
+    public override ExecutionResult ExecuteInstructions(
                     ulong numberOfInstructionsToExecute,
                     out ulong numberOfExecutedInstructions) {
         UInt64 instructionsExecutedThisRound = 0UL;