Kernel: Map special regions according to ExHeader

This replaces the hardcoded VRAM/DSP mappings with ones made based on
the ExHeader ARM11 Kernel caps list. While this has no visible effect
for most applications (since they use a standard set of mappings) it
does improve support for system modules and n3DS exclusives.

src/core/hle/kernel/process.h

@@ -20,7 +20,7 @@ struct AddressMapping {
     // Address and size must be page-aligned
     VAddr address;
     u32 size;
-    bool writable;
+    bool read_only;
     bool unk_flag;
 };