usb: chipidea: usbmisc_imx: Move the reading of USB_PHY_CTRL

If 'evdo' property is not defined, then reading the MX25_USB_PHY_CTRL_OFFSET
register is an unneeded operation.

Move the reading of MX25_USB_PHY_CTRL_OFFSET inside the 'evdo' if block code,
where it is actually used.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>