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/fs/archive.cpp

@@ -40,8 +40,7 @@
 #include "core/hle/service/service.h"
 #include "core/memory.h"
 
-namespace Service {
-namespace FS {
+namespace Service::FS {
 
 // Command to access directory
 enum class DirectoryCommand : u32 {
@@ -701,5 +700,4 @@ void ArchiveShutdown() {
     UnregisterArchiveTypes();
 }
 
-} // namespace FS
-} // namespace Service
+} // namespace Service::FS

src/core/hle/service/fs/archive.h

@@ -28,8 +28,7 @@ namespace Loader {
 class AppLoader;
 }
 
-namespace Service {
-namespace FS {
+namespace Service::FS {
 
 /// Supported archive types
 enum class ArchiveIdCode : u32 {
@@ -296,5 +295,4 @@ void RegisterArchiveTypes();
 /// Unregister all archive types
 void UnregisterArchiveTypes();
 
-} // namespace FS
-} // namespace Service
+} // namespace Service::FS

src/core/hle/service/fs/fs_user.cpp

@@ -30,8 +30,7 @@ using Kernel::ClientSession;
 using Kernel::ServerSession;
 using Kernel::SharedPtr;
 
-namespace Service {
-namespace FS {
+namespace Service::FS {
 
 void FS_USER::Initialize(Kernel::HLERequestContext& ctx) {
     IPC::RequestParser rp(ctx, 0x0801, 0, 2);
@@ -857,5 +856,4 @@ FS_USER::FS_USER() : ServiceFramework("fs:USER", 30) {
 void InstallInterfaces(SM::ServiceManager& service_manager) {
     std::make_shared<FS_USER>()->InstallAsService(service_manager);
 }
-} // namespace FS
-} // namespace Service
+} // namespace Service::FS

src/core/hle/service/fs/fs_user.h

@@ -7,8 +7,7 @@
 #include "common/common_types.h"
 #include "core/hle/service/service.h"
 
-namespace Service {
-namespace FS {
+namespace Service::FS {
 
 class FS_USER final : public ServiceFramework<FS_USER> {
 public:
@@ -520,5 +519,4 @@ private:
 
 void InstallInterfaces(SM::ServiceManager& service_manager);
 
-} // namespace FS
-} // namespace Service
+} // namespace Service::FS