Staging: hv: util: kvp: Cleanup kvp_get_domain_name()

Cleanup kvp_get_domain_name(). If getaddrinfo() fails, deal with it properly
(this can happen if no IP address has been assigned). Also, don't specify
a specific service in the call to getaddrinfo() to make this code as generic
as possible. Lastly, move the call to gethostname() after the local variables.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>