[M] Change in flashrom[master]: writeprotect: skip unnecessary writes

[Edward O'Callaghan (Code Review)]

Attention is currently required from: Nico Huber, Sergii Dmytruk.

Edward O'Callaghan has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/66754 )

Change subject: writeprotect: skip unnecessary writes
......................................................................

Patch Set 1: Code-Review+1

(4 comments)

Commit Message:

https://review.coreboot.org/c/flashrom/+/66754/comment/f939e2dd_fd9f7ada 
PS1, Line 7: writeprotect
nit: `writeprotect.c:`

File writeprotect.c:

https://review.coreboot.org/c/flashrom/+/66754/comment/e70cebcb_ac082f6a 
PS1, Line 158: old
`actual`

https://review.coreboot.org/c/flashrom/+/66754/comment/bd0e1cd2_131c2db4 
PS1, Line 159: new
`expected`

https://review.coreboot.org/c/flashrom/+/66754/comment/0ad0dc3c_cc9d8fe2 
PS1, Line 160: old == new
You may reuse the result from line159 one line163,

```
if (actual == expected)
    continue;

value = (value & ~write_masks[reg]) | expected;

if (wp_write_register(flash, reg, value))
    return FLASHROM_WP_ERR_WRITE_FAILED;
}
```