[lldb] Remove an outdated comment. NFC.

This comment became outdated in 053eb35651
(but was moved along); that commit moved the code and the comment
to a separate function, with a separate local variable
`num_of_bytes_read`. On error, the possibly garbage value is never
copied back to the caller's reference, thus the comment is no longer
relevant (and slightly confusing as is).

Differential Revision: https://reviews.llvm.org/D128226

lldb/source/Plugins/Process/Windows/Common/ProcessDebugger.cpp

@@ -281,10 +281,6 @@ Status ProcessDebugger::ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
   SIZE_T num_of_bytes_read = 0;
   if (!::ReadProcessMemory(process.GetNativeProcess().GetSystemHandle(), addr,
                            buf, size, &num_of_bytes_read)) {
-    // Reading from the process can fail for a number of reasons - set the
-    // error code and make sure that the number of bytes read is set back to 0
-    // because in some scenarios the value of bytes_read returned from the API
-    // is garbage.
     error.SetError(GetLastError(), eErrorTypeWin32);
     LLDB_LOG(log, "reading failed with error: {0}", error);
   } else {