Mappings are done with vaddr=paddr.
- I/O space mapped with two gigapages
- Kernel space mapped to statically allocated page tables. 2MB of kernel
memory is supported.
- Page pool is mapped to the kernel space, to allow virtual memory access
for the kernel e.g. to initialize the page memory when it is allocated.
Move the target specific memory map to a separate file so there is no
need to copy&paste the __xxram_start etc linker symbols to each file
that needs them.
Also add MMU flags for I/O and kernel areas, they will be needed
when the kernel runs with virtual addresses also.