net: stmmac: remove priv->dma_cap.eee test in tx_lpi methods

net: stmmac: remove priv->dma_cap.eee test in tx_lpi methods

The tests for priv->dma_cap.eee in stmmac_mac_{en,dis}able_tx_lpi()
is useless as these methods will only be called when using phylink
managed EEE, and that will only be enabled if the LPI capabilities
in phylink_config have been populated during initialisation. This
only occurs when priv->dma_cap.eee was true.

As priv->dma_cap.eee remains constant during the lifetime of the driver
instance, there is no need to re-check it in these methods.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1tffdN-003ZHt-Mq@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>