hvc_xen: avoid uninitialized variable warning
hvc_xen: avoid uninitialized variable warning

Older compilers don't recognize that "v" can't be used uninitialized;
other code using hvm_get_parameter() zeros the value too, so follow
suit here.

Signed-off-by: Jan Beulich <01de09643e0ae62e116f8bd77de435799874b456@suse.com>
Signed-off-by: David Vrabel <b9d45bd1f671e508cd8daa63dfc3cabb597562df@citrix.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs