idmap2: fix clang-tidy warnings [modernize-*]

Bug: 120024673
Test: mmm frameworks/base/cmds/idmap2; check output
Change-Id: I8768169fb7b541eb6b1aa3311c46a710eb71aac9
diff --git a/cmds/idmap2/libidmap2/BinaryStreamVisitor.cpp b/cmds/idmap2/libidmap2/BinaryStreamVisitor.cpp
index b7765bc..9651328 100644
--- a/cmds/idmap2/libidmap2/BinaryStreamVisitor.cpp
+++ b/cmds/idmap2/libidmap2/BinaryStreamVisitor.cpp
@@ -22,8 +22,7 @@
 
 #include "idmap2/BinaryStreamVisitor.h"
 
-namespace android {
-namespace idmap2 {
+namespace android::idmap2 {
 
 void BinaryStreamVisitor::Write16(uint16_t value) {
   uint16_t x = htodl(value);
@@ -77,5 +76,4 @@
   }
 }
 
-}  // namespace idmap2
-}  // namespace android
+}  // namespace android::idmap2