these register definitions are common to all cortex mcus. some of the
registers might not be implemented everywhere (especially the floating
point registers), but defining them does no harm.
this modification does not result in any changes in the example
binaries.
Only add one linker script per eval board, and have the Makefiles use that.
This avoids duplication, and various copy-paste errors and left-overs
which we already have in the tree.
Some of the linker scripts are not really correct, yet. Both, the comments
which say which board, chip, and RAM/ROM sizes are used, as well as the
actual RAM/ROM size definitions are sometimes copy-pasted from other boards
and are thus incorrect. This needs to be fixed.