Use `.value()` instead of `*`.

`&*` looks very confusing.

Change-Id: If21fa13ac59bc2e315f9b7821b35f99af27a128f
Test: Presubmit
diff --git a/runtime/oat_file_assistant.cc b/runtime/oat_file_assistant.cc
index 01a2564..984c053 100644
--- a/runtime/oat_file_assistant.cc
+++ b/runtime/oat_file_assistant.cc
@@ -775,7 +775,7 @@
   }
 
   if (cached_required_dex_checksums_.has_value()) {
-    return &*cached_required_dex_checksums_;
+    return &cached_required_dex_checksums_.value();
   } else {
     *error_msg = cached_required_dex_checksums_error_;
     DCHECK(!error_msg->empty());