usb: otg: isp1301_omap: fix compile error

commit 91c8a5a9 broke
compilation of this driver after it introduced
otg_init() as a static inline in <linux/usb/otg.h>

Reported-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>