vmci: fix panic due to freeing unallocated resources

[mp]

Summary

An error mapping PCI resources results in a panic due to unallocated
resources being freed up. This change puts the appropriate checks in
place to prevent the panic.

PR: 252445
Reported by: Marek Zarychta <[e-mail]>
Tested by: marcus
MFC after: 1 week
Sponsored by: VMware

Test Plan

Along with user testing, also simulated error by inserting a ENXIO
return in vmci_map_bars().

[marcus]

This looks good to me and works on my old ESX server.