Add the hidden-from-probing chips category and make KB9012 hidden

There are some chips like ENE KB9012, probing for which
could cause the other chips to misbehave. Therefore, such chips
should be "hidden" - not probed for unless the user wants

This commit introduces a new field to the "flashchip" structure:

int hidden;

Now it is possible to "hide" any chip by adding this line

 .hidden        = 1,

to the "struct flashchip flashchips[]" structure of a chip, like

 .write         = edi_chip_write,
 .read          = edi_chip_read,
 .voltage       = {2700, 3600},
 .hidden        = 1,
 },

^^^ KB9012 has been "hidden" this way, and it will never be probed for
unless explicitly specified by its' chip name: --chip "KB9012 (EDI)"

Now, flashrom will probe for a chip only if one of these conditions is true:
1) no chip has been specified AND this chip is not "hidden"
2) this chip has been specified by -c | --chip <chipname>

Change-Id: I89a53ccaef2791a2ac32904d7ab813da7478a6f0
Signed-off-by: Mike Banon <mikebdp2@gmail.com>
---
M flash.h
M flashchips.c
M flashrom.c
3 files changed, 17 insertions(+), 1 deletion(-)