i7core_edac: Introduce i7core_pci_ctl_create/release

Have a couple of method.
while here sort out lines in the i7core_register_mci() a bit.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>