net: ethernet: ti: cpsw_ethtool: fix ethtool ring param set

net: ethernet: ti: cpsw_ethtool: fix ethtool ring param set

[ Upstream commit 09faf5a7d7c0bcb07faba072f611937af9dd5788 ]

Fix ability to set RX descriptor number, the reason - initially
"tx_max_pending" was set incorrectly, but the issue appears after
adding sanity check, so fix is for "sanity" patch.

Fixes: 37e2d99b59c476 ("ethtool: Ensure new ring parameters are within bounds during SRINGPARAM")
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>