Fix lpc11xx magic number programming when chunks overlap

In the case where the vectors are in a separate section smaller than
the chunksize, the lpc11xx magic number calculation could generate an
incorrect value.
Merge branch 'lpc11xx-flash' of https://github.com/John-Titor/blackmagic into John-Titor-lpc11xx-flash

Conflicts:
	src/lpc11xx.c
Merge branch 'John-Titor-lpc11xx-flash'