iplink_can: add initial CAN XL support

This is the iproute2 counterpart of Linux kernel's commit e63281614747
("can: netlink: add initial CAN XL support").

CAN XL uses bittiming parameters different from Classical CAN and CAN FD.
Thus, all the data bittiming parameters, including TDC, need to be
duplicated for CAN XL.

Add the "xl" option to iplink_can which controls the CAN_CTRLMODE_XL flag
of the netlink interface. Then add the "xbitrate", "xsample-point", "xtq",
"xprop-seg", "xphase-seg1", "xphase-seg2", "xsjw", "xtdcv", "xtdco",
"xtdcf" and "xtdc-mode" which are all sub options of "xl". Add the logic to
query and print all those values. Update print_usage() accordingly.

All these options behave similarly to their CAN FD equivalent.

The new options which are specific to CAN XL (i.e. not inherited from CAN
FD) will be added in a subsequent change.

Example using the dummy_can driver:

  # modprobe dummy_can
  # ip link set can0 type can bitrate 500000 fd on dbitrate 2000000 xl on xbitrate 8000000
  $ ip --details link show can0
  5: can0: <NOARP> mtu 2060 qdisc noop state DOWN mode DEFAULT group default qlen 10
      link/can  promiscuity 0 allmulti 0 minmtu 76 maxmtu 2060
      can <FD,TDC-AUTO,XL,XL-TDC-AUTO> state STOPPED restart-ms 0
  	  bitrate 500000 sample-point 0.875
  	  tq 12 prop-seg 69 phase-seg1 70 phase-seg2 20 sjw 10 brp 2
  	  dummy_can CC: tseg1 2..256 tseg2 2..128 sjw 1..128 brp 1..512 brp_inc 1
  	  dbitrate 2000000 dsample-point 0.750
  	  dtq 6 dprop-seg 29 dphase-seg1 30 dphase-seg2 20 dsjw 10 dbrp 1
  	  tdco 60 tdcf 0
  	  dummy_can FD: dtseg1 2..256 dtseg2 2..128 dsjw 1..128 dbrp 1..512 dbrp_inc 1
  	  tdco 0..127 tdcf 0..127
  	  xbitrate 8000000 xsample-point 0.750
  	  xtq 6 xprop-seg 7 xphase-seg1 7 xphase-seg2 5 xsjw 2 xbrp 1
  	  xtdco 15 xtdcf 0
  	  dummy_can XL: xtseg1 2..256 xtseg2 2..128 xsjw 1..128 xbrp 1..512 xbrp_inc 1
  	  xtdco 0..127 xtdcf 0..127
  	  clock 160000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 tso_max_size 65536 tso_max_segs 65535 gro_max_size 65536 gso_ipv4_max_size 65536 gro_ipv4_max_size 65536

Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>