[DWARF][BOLT] Handle getBinaryFunctionContainingAddress returning nullptr for DW_TAG_call_site

DW_TAG_call_site/DW_AT_call_return_pc can contain address that is not in any
function. In this case getBinaryFunctionContainingAddress returns nullptr. For
this case preserving original address.

Reviewed By: rafauler

Differential Revision: https://reviews.llvm.org/D132057