[offload] Fix build with debug libomptarget (#159144)

Currently get this error
```
offload/plugins-nextgen/common/src/PluginInterface.cpp:859:63: error: member reference type 'StringRef' is not a pointer; did you mean to use '.'?
```

We pass the full image binary now so we can't really print anything
useful here.

Seems introduced in #158748.

---------

Signed-off-by: Sarnie, Nick <[email protected]>
Co-authored-by: Joseph Huber <[email protected]>

Author: sarnex

offload/plugins-nextgen/common/src/PluginInterface.cpp

@@ -856,7 +856,7 @@ Error GenericDeviceTy::deinit(GenericPluginTy &Plugin) {
 }
 Expected<DeviceImageTy *> GenericDeviceTy::loadBinary(GenericPluginTy &Plugin,
                                                       StringRef InputTgtImage) {
-  DP("Load data from image " DPxMOD "\n", DPxPTR(InputTgtImage->ImageStart));
+  DP("Load data from image " DPxMOD "\n", DPxPTR(InputTgtImage.bytes_begin()));
 
   std::unique_ptr<MemoryBuffer> Buffer;
   if (identify_magic(InputTgtImage) == file_magic::bitcode) {