tools/xl: use libxl_domain_info to get domain type for vcpu-pin

tools/xl: use libxl_domain_info to get domain type for vcpu-pin

Parsing the config seems to be an overkill for this particular task
and the config might simply be absent. Type returned from libxl_domain_info
should be either LIBXL_DOMAIN_TYPE_HVM or LIBXL_DOMAIN_TYPE_PV but in
that context distinction between PVH and HVM should be irrelevant.

Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
(cherry picked from commit 48dab9767d2eb173495707cb1fd8ceaf73604ac1)
(cherry picked from commit c59579d8319b776ae6243da1999737e2b4737710)