i40e: don't remove HMC that doesn't exist

If a reset recovery failed (e.g. firmware is broken), the HMC space won't
get set up.  We don't need to try to delete it if it didn't get set up.
This stops some needless error messages when we already know we need to
just tear things down.

Change-ID: Iac600481765e20b136052b43a544e55d7870268b
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>