masterd.instance: Add missing argument
masterd.instance: Add missing argument

_DiskTransferPrivate takes three parameters, not two.

Signed-off-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>
Reviewed-by: Manuel Franceschini <db39c5e3ea8a0dd522b695359ee443fe7b25ffd4@google.com>

bitemyapp/ganeti,ganeti/ganeti,yiannist/ganeti,andir/ganeti,bitemyapp/ganeti,mbakke/ganeti,grnet/snf-ganeti,apyrgio/ganeti,apyrgio/snf-ganeti,yiannist/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,dimara/ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,onponomarev/ganeti,ganeti/ganeti,leshchevds/ganeti,apyrgio/snf-ganeti,apyrgio/ganeti,grnet/snf-ganeti,leshchevds/ganeti,ganeti/ganeti,leshchevds/ganeti,andir/ganeti,onponomarev/ganeti,mbakke/ganeti,dimara/ganeti,yiannist/ganeti