libnfc: bump version to recent svn revision

The libnfc package is currently at version 1.5.1 in Buildroot. This patch
bumps the version to a recent svn revision, for the following reasons.

* Version 1.5.1 is marked as "unstable" on the libnfc download site.

* The nfc-tools project at

    http://code.google.com/p/nfc-tools/



  includes a library that extends libnfc with LLCP functionality.
  Unfortunately, to build this requires a libnfc version no lower than 1.6.
  The version 1.6.0-rc1 Release Candidate does not build; svn commits to fix
  the build problems have not yet been back-ported into a Release Candidate.

* The libfreefare package is currently at version 0.3.2 in Buildroot. To bump
  this to the most recent version (0.3.4) also requires a libnfc version no
  lower than 1.6.

I suggest that this patch be regarded as a temporary fix, pending the release
of libnfc 1.6, which will allow other dependent packages to be progressed in
the interim.

Signed-off-by: Simon Dawson <spdawson@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>