ice: check if VF exists before mode check

commit 83b49e7f upstream.

Setting trust on VF should return EINVAL when there is no VF. Move
checking for switchdev mode after checking if VF exists.

Fixes: c54d209c ("ice: Wait for VF to be reset/ready before configuration")
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@intel.com>
Signed-off-by: Kalyan Kodamagula <kalyan.kodamagula@intel.com>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Liwei Song <liwei.song@windriver.com>