These definitions have ended up being chip specific. Moving them into
respective soc_memory_layout.c makes the whole picture of memory
regions easier to see, and also makes adding support for new chips
easier.
No longer necessary to keep all reserved addresses in 'soc'.
Means 'soc' does not need to know about 'bt', for example.
Also means that Bluetooth can be enabled in config without any memory being reserved for BT
controller. Only if code calling the BT controller is linked in, will this memory be reserved...
