PowerPC: Move MMU-specifics from PowerPC.h to MMU.h

PowerPC.h at this point is pretty much a general glob of stuff, and it's
unfortunate, since it means pulling in a lot of unrelated header
dependencies and a bunch of other things that don't need to be seen by
things that just want to read memory.

Breaking this out into its own header keeps all the MMU-related stuff
together and also limits the amount of header dependencies being
included (the primary motivation for this being the former reason).

Source/Core/Core/HLE/HLE_Misc.cpp

@@ -4,11 +4,12 @@
 
 #include "Core/HLE/HLE_Misc.h"
 
+#include "Common/Common.h"
 #include "Common/CommonTypes.h"
-#include "Common/Logging/Log.h"
 #include "Core/GeckoCode.h"
 #include "Core/HW/CPU.h"
 #include "Core/Host.h"
+#include "Core/PowerPC/MMU.h"
 #include "Core/PowerPC/PowerPC.h"
 
 namespace HLE_Misc

Source/Core/Core/HLE/HLE_OS.cpp

@@ -12,6 +12,7 @@
 #include "Common/MsgHandler.h"
 #include "Common/StringUtil.h"
 #include "Core/HLE/HLE_VarArgs.h"
+#include "Core/PowerPC/MMU.h"
 #include "Core/PowerPC/PowerPC.h"
 
 namespace HLE_OS

Source/Core/Core/HLE/HLE_VarArgs.h

@@ -7,7 +7,7 @@
 #include "Common/Align.h"
 #include "Common/CommonTypes.h"
 
-#include "Core/HW/Memmap.h"
+#include "Core/PowerPC/MMU.h"
 #include "Core/PowerPC/PowerPC.h"
 
 #include <type_traits>