[coreboot] #104: flashrom: Change flash drivers to never erase data before writing

[FENG Yu Ning]

We are talking about choosing some options from the full list:

* chip read
* chip erase
  chip write (0xff to other)
* chip erase-and-write (option 'write')

  partial read
  partial erase
1 partial write
2 partial erase-and-write

* = Options we have
1 = Carl-Daniel suggests
2 = Other people suggest

Every option in the list is useful in some case. My opinion on -

the choice	- Support the full list;
1		- Warning and ask for continuation. No checking for 0xff;
2		- We need this convenience for partial modification.

My two cents.

yu ning