[presubmit] Enable readability/namespace linter checking.

src/ppc/assembler-ppc-inl.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
 // are met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 702 matching lines @@
     *p = instr1;
     *(p + 1) = instr2;
     if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
       Assembler::FlushICacheWithoutIsolate(p, 2 * kInstrSize);
     }
 #endif
     return;
   }
   UNREACHABLE();
 }
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_PPC_ASSEMBLER_PPC_INL_H_