Don't implicitly dereference DW_CFA_def_cfa_expression.

The specification isn't entirely clear. Follow the gdb interpretation.

Bug: 73954823
Test: libunwindstack_test
Change-Id: If72717f54eed84e442f43af19e615143a9796b68
diff --git a/libunwindstack/DwarfSection.cpp b/libunwindstack/DwarfSection.cpp
index 7649798..ddbc12e 100644
--- a/libunwindstack/DwarfSection.cpp
+++ b/libunwindstack/DwarfSection.cpp
@@ -214,21 +214,13 @@
       }
       eval_info.cfa += loc->values[1];
       break;
-    case DWARF_LOCATION_EXPRESSION:
     case DWARF_LOCATION_VAL_EXPRESSION: {
       AddressType value;
       if (!EvalExpression(*loc, regular_memory, &value, &eval_info.regs_info, nullptr)) {
         return false;
       }
-      if (loc->type == DWARF_LOCATION_EXPRESSION) {
-        if (!regular_memory->ReadFully(value, &eval_info.cfa, sizeof(AddressType))) {
-          last_error_.code = DWARF_ERROR_MEMORY_INVALID;
-          last_error_.address = value;
-          return false;
-        }
-      } else {
-        eval_info.cfa = value;
-      }
+      // There is only one type of valid expression for CFA evaluation.
+      eval_info.cfa = value;
       break;
     }
     default: