mtd/at25ee.c: Fix write check condition

Fix writing till the very last byte of the memory

Signed-off-by: Antoine Juckler <6445757+ajuckler@users.noreply.github.com>

drivers/mtd/at25ee.c

@@ -667,7 +667,7 @@ static ssize_t at25ee_write(FAR struct mtd_dev_s *dev, off_t offset,
 
   /* Forbid writes past the end of the device */
 
-  if (nbytes + offset >= priv->size)
+  if (nbytes + offset > priv->size)
     {
       return 0;
     }