sched/debug: Fix the alignment of the show-state debug output

Current sysrq(t) output task fields name are not aligned with
actual task fields value, e.g.:

	kernel: sysrq: Show State
	kernel:  task                        PC stack   pid father
	kernel: systemd         S12456     1      0 0x00000000
	kernel: Call Trace:
	kernel: ? __schedule+0x240/0x740

To make it more readable, print fields name together with task fields
value in the same line, with fixed width:

	kernel: sysrq: Show State
	kernel: task:systemd         state:S stack:12920 pid:    1 ppid:     0 flags:0x00000000
	kernel: Call Trace:
	kernel: __schedule+0x282/0x620

Signed-off-by: Libing Zhou <libing.zhou@nokia-sbell.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200814030236.37835-1-libing.zhou@nokia-sbell.com