USB: r8a66597-hcd: fix interrupt transfer interval

This driver ignored the value of bInterval and revised the problem
that performed interrupt transfer.

ASIX USB Ethernet adapter comes to work with this host controller
by applying this patch.

Signed-off-by: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>