perf kvm: Fix spurious '=' use in man page

perf kvm: Fix spurious '=' use in man page

As option --host and --guest request no input for it, there should not
be a '=' after them in the man page sources.

And --output expects a filename as the input, so there should be a '='
after it.

This patch removes the needless '=' after --guest and --host, and adds a
'=' after --output in perf-kvm.txt.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/6124d9eb10a3f1f6b399d1db660110bc7a60fd6b.1386197481.git.yangds.fnst@cn.fujitsu.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>