net: phy: smsc: LAN8710/20: remove PHY_RST_AFTER_CLK_EN flag

Don't reset the phy without respect to the PHY library state machine
because this breaks the phy IRQ mode. The same behaviour can be archived
now by specifying the refclk.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>