usb: chipidea: i.MX: use devm_usb_get_phy_by_phandle to get phy

This patch converts the driver to use devm_usb_get_phy_by_phandle
which makes the code smaller and a bit simpler.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>