NFC: digital: NFC-DEP Target WT(nfcdep,max) is now 14

Version 1.1 of the NFC Forum's NFC Digital Protocol Technical
Specification dated 2014-07-14 specifies that the NFC-DEP Protocol's
Target WT(nfcdep,max) value is 14.  In version 1.0 it was 8 so change
the value in the Linux NFC-DEP Protocol code accordingly.

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>