MC: Remove MCSubtargetInfo::InitCPUSched()

Remove all calls to `MCSubtargetInfo::InitCPUSched()` and merge its body
into the only relevant caller, `MCSubtargetInfo::InitMCProcessorInfo()`.
We were only calling the former after explicitly calling the latter with
the same CPU; it's confusing to have both methods exposed.

Besides a minor (surely unmeasurable) speedup in ARM and X86 from
avoiding running the logic twice, no functionality change.

llvm-svn: 241956
diff --git a/llvm/lib/Target/X86/X86Subtarget.cpp b/llvm/lib/Target/X86/X86Subtarget.cpp
index 758d2b0..dff3624 100644
--- a/llvm/lib/Target/X86/X86Subtarget.cpp
+++ b/llvm/lib/Target/X86/X86Subtarget.cpp
@@ -192,12 +192,9 @@
       FullFS = "+64bit,+sse2";
   }
 
-  // If feature string is not empty, parse features string.
+  // Parse features string and set the CPU.
   ParseSubtargetFeatures(CPUName, FullFS);
 
-  // Make sure the right MCSchedModel is used.
-  InitCPUSchedModel(CPUName);
-
   InstrItins = getInstrItineraryForCPU(CPUName);
 
   // It's important to keep the MCSubtargetInfo feature bits in sync with