I've accidentally specified just half of the available flash in the
linker script. This change fixes that.
There is in fact a 256kB version of the nrf52832, but it also has 32kB
of RAM so if you had used that it wouldn't actually work right now.
Also, extending the available flash should not affect existing programs
(as I haven't seen any run into size limitations yet).
The RAM base address is needed during SoftDevice initialization. So far,
the same magic value has been used in aykevl/go-bluetooth and in TinyGo,
but this should be configured in only one place.
This will have additional benefits in the future:
* It is currently set to 0x39c0, which is around 14.5kB. Most nrf51822
chips have only 16kB of RAM, so this is way too much for those
chips.
* LLD in LLVM 11 allows expressions in the MEMORY part of linker
scripts, which will allow overriding the SoftDevice RAM area with a
linker flag, which might come in handy.
