Memory: Move address type conversion routines to memory.cpp/h

These helpers aren't really part of the kernel, and mem_map.cpp/h is
going to be moved there next.

src/core/memory.h

@@ -123,6 +123,17 @@ void WriteBlock(VAddr addr, const u8* data, size_t size);
 
 u8* GetPointer(VAddr virtual_address);
 
+/**
+* Converts a virtual address inside a region with 1:1 mapping to physical memory to a physical
+* address. This should be used by services to translate addresses for use by the hardware.
+*/
+PAddr VirtualToPhysicalAddress(VAddr addr);
+
+/**
+* Undoes a mapping performed by VirtualToPhysicalAddress().
+*/
+VAddr PhysicalToVirtualAddress(PAddr addr);
+
 /**
  * Gets a pointer to the memory region beginning at the specified physical address.
  *