Fix the use of nic type, which results in the following for each type
of domain:
* HVM: let the user choose, if none specified use VIF_IOEMU.
* PV: use VIF is none provided, return error if VIF_IOEMU requested.
Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>