devlink: Fix fmsg nesting in non JSON output

devlink: Fix fmsg nesting in non JSON output

When an object or an array opening follows a name (label), add a new
line and indentation before printing the label. When name (label) is
followed by a value, print both at the same line.

Prior to this patch nesting was not visible in a non JSON output:
JSON:
{
    "Common config": {
        "SQ": {
            "stride size": 64,
            "size": 1024
        },
        "CQ": {
            "stride size": 64,
            "size": 1024
        } },
    "SQs": [ {
            "channel ix": 0,
            "sqn": 10,
            "HW state": 1,
            "stopped": false,
            "cc": 0,
            "pc": 0,
            "CQ": {
                "cqn": 6,
                "HW status": 0
            }
         },{
            "channel ix": 0,
            "sqn": 14,
            "HW state": 1,
            "stopped": false,
            "cc": 0,
            "pc": 0,
            "CQ": {
                "cqn": 10,
                "HW status": 0
            }
         } ]
}

Before this patch:
Common Config: SQ: stride size: 64 size: 1024
CQ: stride size: 64 size: 1024
SQs:
  channel ix: 0 tc: 0 txq ix: 0 sqn: 10 HW state: 1 stopped: false cc: 0 pc: 0 CQ: cqn: 6 HW status: 0
  channel ix: 1 tc: 0 txq ix: 1 sqn: 14 HW state: 1 stopped: false cc: 0 pc: 0 CQ: cqn: 10 HW status: 0

With this patch:
Common config:
  SQ:
    stride size: 64 size: 1024
    CQ:
      stride size: 64 size: 1024
SQs:
  channel ix: 0 sqn: 10 HW state: 1 stopped: false cc: 0 pc: 0
  CQ:
    cqn: 6 HW status: 0
  channel ix: 1 sqn: 14 HW state: 1 stopped: false cc: 0 pc: 0
  CQ:
    cqn: 10 HW status: 0

Fixes: 7b8baf834d5e ("devlink: Add devlink health diagnose command")
Signed-off-by: Aya Levin <ayal@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>