tree: Change signature of extract_programmer_param_str()

Results can be reproduced with the following invocation;
```
 $ find -name '*.c' -exec sed -i 's/extract_programmer_param_str(/extract_programmer_param_str(NULL, /g' '{}' \;
```

This allows for a pointer to the actual programmer parameters
to be passed instead of a global.

Change-Id: I781a328fa280e0a9601050dd99a75af72c39c899
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/66654
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>

linux_mtd.c

@@ -500,7 +500,7 @@ static int linux_mtd_init(void)
 	int ret = 1;
 	struct linux_mtd_data *data = NULL;
 
-	param_str = extract_programmer_param_str("dev");
+	param_str = extract_programmer_param_str(NULL, "dev");
 	if (param_str) {
 		char *endptr;