usb: gadget: renesas_usbhs: fixup struct completion usage

Since renesas_usbhs mod_host didn't use
struct completion as static object, the warning of lockdep came out.
This patch fixup this issue.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>