Audio HAL: Simplify types updates for 'common' and 'audio' packages

Instead of importing every single type individually ("using <type>"),
import entire namespaces of
::android::hardware::audio::CPP_VERSION and
::android::hardware::audio::common::CPP_VERSION
inside the "implementation" namespace in the default implementation.

This simplifies modifying types, as it is not needed anymore
to surround "using <type>" directives with #if MAJOR_VERSION ...

Note that the contents of the namespaces are imported inside
the "implementation" namespace, which reduces risks of name collision

Also, fixed the namespace for HidlUtils--it needs to be in
'implementation'.

Test: make
Change-Id: I81bbb3074b5763717ae72e747a075fd46dc36d18
diff --git a/audio/common/all-versions/default/HidlUtils.h b/audio/common/all-versions/default/HidlUtils.h
index 77c8b89..758a7f4 100644
--- a/audio/common/all-versions/default/HidlUtils.h
+++ b/audio/common/all-versions/default/HidlUtils.h
@@ -24,19 +24,15 @@
 #include <system/audio.h>
 
 using ::android::hardware::hidl_vec;
-using ::android::hardware::audio::common::CPP_VERSION::AudioConfig;
-using ::android::hardware::audio::common::CPP_VERSION::AudioGain;
-using ::android::hardware::audio::common::CPP_VERSION::AudioGainConfig;
-using ::android::hardware::audio::common::CPP_VERSION::AudioOffloadInfo;
-using ::android::hardware::audio::common::CPP_VERSION::AudioPort;
-using ::android::hardware::audio::common::CPP_VERSION::AudioPortConfig;
-using ::android::hardware::audio::common::CPP_VERSION::Uuid;
 
 namespace android {
 namespace hardware {
 namespace audio {
 namespace common {
 namespace CPP_VERSION {
+namespace implementation {
+
+using namespace ::android::hardware::audio::common::CPP_VERSION;
 
 class HidlUtils {
    public:
@@ -69,6 +65,7 @@
     static void uuidToHal(const Uuid& uuid, audio_uuid_t* halUuid);
 };
 
+}  // namespace implementation
 }  // namespace CPP_VERSION
 }  // namespace common
 }  // namespace audio