[llvm-mca] Update the help text to reflect "physical" registers. NFC.

llvm-svn: 338430

llvm/tools/llvm-mca/llvm-mca.cpp

@@ -96,7 +96,7 @@ static cl::opt<unsigned>
 
 static cl::opt<unsigned>
     RegisterFileSize("register-file-size",
-                     cl::desc("Maximum number of temporary registers which can "
+                     cl::desc("Maximum number of physical registers which can "
                               "be used for register mappings"),
                      cl::cat(ToolOptions), cl::init(0));