memory: Dehardcode the use of a 36-bit address space

Given games can also request a 32-bit or 39-bit address space, we
shouldn't be hardcoding the address space range as 36-bit.

src/core/hle/kernel/vm_manager.h

@@ -205,6 +205,9 @@ public:
     /// Gets the total address space address size, used by svcGetInfo
     u64 GetAddressSpaceSize() const;
 
+    /// Gets the address space width in bits.
+    u64 GetAddressSpaceWidth() const;
+
     /// Gets the base address of the code region.
     VAddr GetCodeRegionBaseAddress() const;