usb: renesas_usbhs: don't re-allocation pipe buffer

Because pipe buffer allocation is very picky and difficult,
current renesas_usbhs driver is not caring pipe re-allocation.

In this situation, driver will create new pipe without caring old pipe
if "usbhsg_ep_enable" is called after "usbhsg_ep_disable" on current driver.
This mean the limited pipe and buffer will be used as waste.
But it is possible to re-use same buffer to same pipe.

By this patch, driver will initialize pipe when it detected new connection or
new gadget, and doesn't try re-allocation for same pipe in above case.

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