ARM: imx6q: remove BMCR_PDOWN handler in ar8035_phy_fixup()

BMCR_PDOWN is removed by resume handler at803x_resume() in
drivers/net/phy/at803x.c

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>