perf script: Add branch types for VM-Entry and VM-Exit

In preparation to support Intel PT decoding of virtual machine traces, add
branch types for VM-Entry and VM-Exit.

Note they are both treated as "calls" because the VM-Exit transfers control
to a different address.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20210218095801.19576-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>