usb: mtu3: fix failed runtime suspend in host only mode

usb: mtu3: fix failed runtime suspend in host only mode

When the dr_mode is "host", after the host enter runtime suspend,
the mtu3 can't do it, because the mtu3's device wakeup function is
not enabled, instead it's enabled in gadget init function, to fix
the issue, init wakeup early in mtu3's probe()

Fixes: 6b587394c65c ("usb: mtu3: support suspend/resume for dual-role mode")
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reported-by: Tianping Fang <tianping.fang@mediatek.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20220929064459.32522-1-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>