[BOLT][NFC] Remove unused function (#89009)

getFileOffsetFor() was replaced with getFileOffsetForAddress().

Author: maksfb

bolt/include/bolt/Rewrite/RewriteInstance.h

@@ -368,13 +368,6 @@ class RewriteInstance {
   /// rewritten binary.
   void patchBuildID();
 
-  /// Return file offset corresponding to a given virtual address.
-  uint64_t getFileOffsetFor(uint64_t Address) {
-    assert(Address >= NewTextSegmentAddress &&
-           "address in not in the new text segment");
-    return Address - NewTextSegmentAddress + NewTextSegmentOffset;
-  }
-
   /// Return file offset corresponding to a virtual \p Address.
   /// Return 0 if the address has no mapping in the file, including being
   /// part of .bss section.