service: Use nested namespace specifiers where applicable

There were a few places where nested namespace specifiers weren't being
used where they could be within the service code. This amends that to
make the namespacing a tiny bit more compact.

src/core/hle/service/pxi/dev.cpp

@@ -4,8 +4,7 @@
 
 #include "core/hle/service/pxi/dev.h"
 
-namespace Service {
-namespace PXI {
+namespace Service::PXI {
 
 DEV::DEV() : ServiceFramework("pxi:dev", 1) {
     // clang-format off
@@ -32,5 +31,4 @@ DEV::DEV() : ServiceFramework("pxi:dev", 1) {
 
 DEV::~DEV() = default;
 
-} // namespace PXI
-} // namespace Service
+} // namespace Service::PXI

src/core/hle/service/pxi/dev.h

@@ -7,8 +7,7 @@
 #include "core/hle/kernel/kernel.h"
 #include "core/hle/service/service.h"
 
-namespace Service {
-namespace PXI {
+namespace Service::PXI {
 
 /// Interface to "pxi:dev" service
 class DEV final : public ServiceFramework<DEV> {
@@ -17,5 +16,4 @@ public:
     ~DEV();
 };
 
-} // namespace PXI
-} // namespace Service
+} // namespace Service::PXI

src/core/hle/service/pxi/pxi.cpp

@@ -5,12 +5,10 @@
 #include "core/hle/service/pxi/dev.h"
 #include "core/hle/service/pxi/pxi.h"
 
-namespace Service {
-namespace PXI {
+namespace Service::PXI {
 
 void InstallInterfaces(SM::ServiceManager& service_manager) {
     std::make_shared<DEV>()->InstallAsService(service_manager);
 }
 
-} // namespace PXI
-} // namespace Service
+} // namespace Service::PXI

src/core/hle/service/pxi/pxi.h

@@ -6,11 +6,9 @@
 
 #include "core/hle/service/service.h"
 
-namespace Service {
-namespace PXI {
+namespace Service::PXI {
 
 /// Registers all PXI services with the specified service manager.
 void InstallInterfaces(SM::ServiceManager& service_manager);
 
-} // namespace PXI
-} // namespace Service
+} // namespace Service::PXI