video_core: use nested namespaces

src/video_core/command_processor.cpp

@@ -28,9 +28,7 @@
 #include "video_core/vertex_loader.h"
 #include "video_core/video_core.h"
 
-namespace Pica {
-
-namespace CommandProcessor {
+namespace Pica::CommandProcessor {
 
 static int vs_float_regs_counter = 0;
 static u32 vs_uniform_write_buffer[4];
@@ -675,6 +673,4 @@ void ProcessCommandList(const u32* list, u32 size) {
     }
 }
 
-} // namespace CommandProcessor
-
-} // namespace Pica
+} // namespace Pica::CommandProcessor