[arch][arm-m] move some hand coded register inits to the CMSIS struct
[arch][arm-m] move some hand coded register inits to the CMSIS struct

No functional change.

littlekernel/lk,hollanderic/lkstuff,travisg/lk,littlekernel/lk,hollanderic/lkstuff,travisg/lk,hollanderic/lkstuff,hollanderic/lkstuff,littlekernel/lk,travisg/lk,travisg/lk,littlekernel/lk