[clang-format][NFC] Remove a redundant check for null

Missed by llvm#145686

Author: owenca

clang/lib/Format/TokenAnnotator.cpp

@@ -1411,7 +1411,7 @@ class AnnotatingParser {
         if (Prev->isPointerOrReference())
           Prev->setFinalizedType(TT_PointerOrReference);
       } else if ((CurrentToken && CurrentToken->is(tok::numeric_constant)) ||
-                 (Prev && Prev->is(TT_StartOfName) && !Scopes.empty() &&
+                 (Prev->is(TT_StartOfName) && !Scopes.empty() &&
                   Scopes.back() == ST_Class)) {
         Tok->setType(TT_BitFieldColon);
       } else if (Contexts.size() == 1 &&