usb: gadget: Introduce SSP rates and lanes

A USB device controller operating in SuperSpeed Plus may support gen2x1,
gen1x2, and/or gen2x2. Introduce SuperSpeed Plus signaling rate
generation and lane count to usb_gadget with the fields ssp_rate and
max_ssp_rate. The gadget driver can use these to setup the device BOS
descriptor and select the desire operating speed and number of lanes.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/b6d2196dcc3c73747f91abf9a082b20bbe276cc4.1610592135.git.Thinh.Nguyen@synopsys.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>