mcb: Fix error path of mcb_pci_probe

If a MCB PCI Carrier device is IO mapped insted of memory-mapped (which is
currently unsupported by the upstream driver) the probe function bails out
with -ENOTSUPP.

In this case the memory of the PCI device was not unmapped.
Also rename error label to reflect what will happen at the destination (suggested
by Julia Lawall <julia.lawall@lip6.fr>.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@men.de>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>