perf list: Fix group description in the man page

Fix an incorrect description in the 'perf list' manpage. When a group
does not fit into the hardware it is partially scheduled, but does not
error out.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20171010224322.15861-1-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>