usb: renesas_usbhs: mod_host: fixup usbhsh_ureq_free() timing

usbhsh_ureq_free() free ureq which includes ubshs_pkt.
But current driver used usbhs_pkt after freed ureq.
This patch fixup this bug.
Special thanks to Chen

Reported-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>