usb: chipidea: imx: pinctrl for HSIC is optional

For imx chipidea controllers, if they use mxs PHY, they need pinctrl
for HSIC. Otherwise, it doesn't need pinctrl and usbmisc control. Like
imx7d and imx8mm.

Reported-by: André Draszik <git@andred.net>
Signed-off-by: Peter Chen <peter.chen@nxp.com>