LPC43XX: Make sure to align target struct to word alignment
LPC43XX: Add mkboot target command; dont make banks bootable by default.

This used to be done transparently in the write step, however that
breaks the 'verify' command. This is also more flexible for cases
where you want to write a flash bank without ever intending it to
be bootable.
LPC43XX: Add reset command to do a system reset (but not the debug).
LPC43XX: Remove type cast for erase function
LPC: Cleanup regs_size (in bytes).

Also use sizeof() to make it clear why we multiple and divide by 4.
LPC43XX: Make the chunk_offset logic more explicit.
LPC43XX: Force target to use internal clock.

Without this, flash write timing might be incorrect.
Merge pull request #32 from aibara/lpc43xx_updates

Lpc43xx target support updates