at86rf230: remove invalid backoff exponent check

This patch removes the invalid backoff exponent check from driver layer.
This is already handled by nl802154.
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/net/ieee802154/at86rf230.c

@@ -1167,7 +1167,7 @@ at86rf230_set_csma_params(struct ieee802154_hw *hw, u8 min_be, u8 max_be,
 	struct at86rf230_local *lp = hw->priv;
 	int rc;
 
-	if (min_be > max_be || max_be > 8 || retries > 5)
+	if (retries > 5)
 		return -EINVAL;
 
 	rc = at86rf230_write_subreg(lp, SR_MIN_BE, min_be);