With the new mei_phy NFC driver API, the pn544 MEI physical layer is
minimal and similar to the microread one.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
As we may need to support other physical layers, we can avoid linking the
core part into each and every pn544 module.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>