[ADT] Fix comment typos in DenseMap.h (#158457)

- The math is wrong.
- We are discussing "inequality".
- "For example" requires ",".

Author: kazutakahirata

llvm/include/llvm/ADT/DenseMap.h

@@ -372,8 +372,8 @@ class DenseMapBase : public DebugEpochBase {
     // Ensure that "NumEntries * 4 < NumBuckets * 3"
     if (NumEntries == 0)
       return 0;
-    // +1 is required because of the strict equality.
-    // For example if NumEntries is 48, we need to return 401.
+    // +1 is required because of the strict inequality.
+    // For example, if NumEntries is 48, we need to return 128.
     return NextPowerOf2(NumEntries * 4 / 3 + 1);
   }