phy: berlin-usb: don't set device's driver_data

After commit 739ae345 ("phy: berlin-usb: Set drvdata for phy and
use it"), we get the address of priv by phy_get_drvdata(), so there's
no need to set device's driver_data any more. This patch removes the
call of platform_set_drvdata().

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>