[flashrom] enum test_state value for "depends"

[Stefan Tauner]

We currently have an
enum test_state {
    OK = 0,
    NT = 1,	/* Not tested */
    BAD
};

This is used in various arrays, namely those for
boards, board enables, chipsets, programmers, and rayer_spi (LPT)
devices. I'd like to add another state that indicates that support
is configuration-dependent. Most infamous use cases would be boards
with ME chipsets and ME chipsets. Another example is the atavia VT6421A
LPC programmer which works in general, just not all boards due to a not
fully understood offset configuration that is board-specific.

Names... CONFIG is quite long but obvious to understand, CD for
configuration-dependent would suite me too, but I am open to
suggestions. What about DEP?