NFC: nci: non-static functions can not be inline

This fixes a build error that seems to be toochain
dependent (Not seen with gcc v5.1):

In file included from net/nfc/nci/rsp.c:36:0:
net/nfc/nci/rsp.c: In function ‘nci_rsp_packet’:
include/net/nfc/nci_core.h:355:12: error: inlining failed in call to
always_inline ‘nci_prop_rsp_packet’: function body not available
 inline int nci_prop_rsp_packet(struct nci_dev *ndev, __u16 opcode,

Signed-off-by: Robert Dolca <robert.dolca@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>