[AMDGPU] Remove calling conv check on entry function

It is undefined behavior to call a function with a
mismatched calling convention. Rather than crash on
this behavior, it should compile.

Author: jofrn

llvm/lib/Target/AMDGPU/AMDGPUResourceUsageAnalysis.cpp

@@ -256,13 +256,6 @@ AMDGPUResourceUsageAnalysisImpl::analyzeResourceUsage(
 
         const Function *Callee = getCalleeFunction(*CalleeOp);
 
-        // Avoid crashing on undefined behavior with an illegal call to a
-        // kernel. If a callsite's calling convention doesn't match the
-        // function's, it's undefined behavior. If the callsite calling
-        // convention does match, that would have errored earlier.
-        if (Callee && AMDGPU::isEntryFunctionCC(Callee->getCallingConv()))
-          report_fatal_error("invalid call to entry function");
-
         auto isSameFunction = [](const MachineFunction &MF, const Function *F) {
           return F == &MF.getFunction();
         };