perf kvm: Do guest-only counting by default

perf kvm: Do guest-only counting by default

Make use of exclude_guest and exlude_host in perf-kvm to do only
guest-only counting by default.

Cc: Gleb Natapov <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Gleb Natapov <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>
[ committer note: Moved perf_{guest,host} & event_attr_init to util.c ]
[                 so as not to drag more stuff to the python binding]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>