powerpc/xmon: fix task state output

powerpc/xmon: fix task state output

BugLink: https://bugs.launchpad.net/bugs/1951822
[ Upstream commit b1f896ce3542eb2eede5949ee2e481526fae1108 ]

p_state is unsigned since the commit 2f064a59a11f

The patch also uses TASK_RUNNING instead of null.

Fixes: 2f064a59a11f ("sched: Change task_struct::state")
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211026133108.7113-1-kda@linux-powerpc.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>