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>

include/writeprotect.h

@@ -89,4 +89,10 @@ enum flashrom_wp_result wp_get_available_ranges(struct flashrom_wp_ranges **, st
 /* Checks if writeprotect functions can be used with the current flash/programmer */
 bool wp_operations_available(struct flashrom_flashctx *);
 
+/*
+ * Converts a writeprotect config to register values and masks that indicate which register bits affect WP state.
+ * reg_values, bit_masks, and write_masks must all have length of at least MAX_REGISTERS.
+ */
+enum flashrom_wp_result wp_cfg_to_reg_values(uint8_t *reg_values, uint8_t *bit_masks, uint8_t *write_masks, struct flashrom_flashctx *, const struct flashrom_wp_cfg *);
+
 #endif /* !__WRITEPROTECT_H__ */