usb: renesas_usbhs: shrink spin lock area

spin lock was very effective while doing 1 packet send/recv on
current renesas_usbhs driver.
But this lock is enough only
 - modify packet/pipe link
 - modify interrpt mask
 - modify fifo access
This patch shrink spin lock area

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