writeprotect: Add function to get register values and WP bit masks

Add a new wp_cfg_to_reg_values() function that takes a generic wp_cfg
instance and returns the chip-specific values that need to be written to
the chip's registers to enable the specified protection range/mode.

The function returns three values for each chip register:
- reg_values[reg]  - Value writeprotect will write to reg
- bit_masks[reg]   - Bit mask for WP-related bits in reg
- write_masks[reg] - Bit mask for writable WP-related bits in reg
                     (i.e. the ones writeprotect will try to write)

BUG=b:260019525,b:259013033,260020006
BRANCH=none
TEST=ninja test

Change-Id: Ib2a47153b230c9f82bb4eca357c335f2abbacc20
Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/69847
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>

tests/tests.c

@@ -494,6 +494,7 @@ int main(int argc, char *argv[])
 		cmocka_unit_test(wp_init_from_status_dummyflasher_test_success),
 		cmocka_unit_test(full_chip_erase_with_wp_dummyflasher_test_success),
 		cmocka_unit_test(partial_chip_erase_with_wp_dummyflasher_test_success),
+		cmocka_unit_test(wp_get_register_values_and_masks),
 	};
 	ret |= cmocka_run_group_tests_name("chip_wp.c tests", chip_wp_tests, NULL, NULL);