usb: xhci: Add debugfs support for xHCI Port Link Info (PORTLI) register.

usb: xhci: Add debugfs support for xHCI Port Link Info (PORTLI) register.

Each xHCI roothub port has a Port Link Info (PORTLI) register that is
used by USB3 and eUSB2V2 ports.

USB3 ports show link error count, rx lane count, and tx lane count.

eUSB2V2 ports show Rx Data Rate (RDR) and Tx Data Rate (TDR).

Rx/Tx Data Rate is a multiple of USB2 2.0 HS 480 Mb/s data rates,
and is only valid if a eUSB2V2 device is connected (CCS=1).

0 = "USB 2.0 HS" normal HS 480 Mb/s, no eUSB2V2 in use
1 = "HS1" Assymetric eUSB2V2 where this direction runs normal 480Mb/s
2 = "HS2" 960Mb/s
...
10 = "HS10" 4.8 Gb/s, max eUSB2V2 rate

PORTLI is Reserved and preserve "RsvdP" for normal USB2 ports

Sample output of USB3 port PORTLI:
cat /sys/kernel/debug/usb/xhci/0000:00:14.0/ports/port14/portli
0x00000000 LEC=0 RLC=0 TLC=0

Signed-off-by: Rai, Amardeep <amardeep.rai@intel.com>
Co-developed-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20251119142417.2820519-24-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>