Staticize usbmisc_imx6q_drv_init/exit() to fix the following sparse warnings:
drivers/usb/chipidea/usbmisc_imx6q.c:147:12: warning: symbol 'usbmisc_imx6q_drv_init' was not declared. Should it be static?
drivers/usb/chipidea/usbmisc_imx6q.c:153:13: warning: symbol 'usbmisc_imx6q_drv_exit' was not declared. Should it be static?