[configfs] Write correct buffer in configfs. Fixes JB#51896

Signed-off-by: Matti Lehtimäki <matti.lehtimaki@jolla.com>

src/usb_moded-configfs.c

@@ -642,7 +642,7 @@ configfs_write_file(const char *path, const char *text)
         goto EXIT;
     }
 
-    int rc = write(fd, text, size);
+    int rc = write(fd, buff, size);
     if( rc == -1 ) {
         log_err("%s: write failure: %m", path);
         goto EXIT;