NFC: mei: Add a common mei bus API for NFC drivers

This isolates the common code that is required to use an mei bus nfc
device from an NFC HCI drivers. This prepares for future drivers for
NFC chips connected behind an Intel Management Engine controller.
The microread_mei HCI driver is also modified to use that common code.

Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>