MC: Remove most remaining uses of MCSymbolData::getSymbol(), NFC

Remove most remaining calls to `MCSymbolData::getSymbol()`, instead
using the already available `MCSymbol` directly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237829 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed