[RFC] flashchips, writeprotect_ranges: add range decoding function

Allow chips to specify functions that map status register bits to
protection ranges. These are used to enumerate available ranges and
determine the protection state of chips. The patch also adds a range
decoding function for the example chips. Many other chips can also be
handled by it, though some will require different functions (e.g.
MX25L6406 and related chips).

Another approach that has been tried in cros flashrom is maintaining
tables of range data, but it quickly becomes error prone and hard to
validate.

Using a function to interpret the ranges allows compact encoding with
most chips and is flexible enough to allow chips with less predictable
ranges to be handled as well.

BUG=b:195381327,b:153800563
TEST=dumped range tables, checked against datasheets
BRANCH=none

Change-Id: Id163ed80938a946a502ed116e48e8236e36eb203
Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
---
M Makefile
M chipdrivers.h
M flash.h
M flashchips.c
M meson.build
A writeprotect_ranges.c
6 files changed, 109 insertions(+), 1 deletion(-)