RK3399 USB DWC3 controller has a issue that FS/LS devices not
recognized if inserted through USB 3.0 HUB. It's because that
the inter-packet delay between the SSPLIT token to SETUP token
is about 566ns, more then the USB spec requirement.

This patch adds a quirk "snps,dis-tx-ipgap-linecheck-quirk" to
disable the u2mac linestate check to decrease the SSPLIT token
to SETUP token inter-packet delay from 566ns to 466ns.
Signed-off-by: William Wu <william.wu@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>