Remove hardcoded path to libnl3 include directory

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

Index: b/configure.in
===================================================================
--- a/configure.in
+++ b/configure.in
@@ -445,7 +445,6 @@
 			AC_DEFINE(HAVE_LIBNL_3_x,1,[if libnl exists and is version 3.x])
 			AC_DEFINE(HAVE_LIBNL_NLE,1,[libnl has NLE_FAILURE])
 			AC_DEFINE(HAVE_LIBNL_SOCKETS,1,[libnl has new-style socket api])
-			V_INCLS="$V_INCLS -I/usr/include/libnl3"
 			have_any_nl="yes"
 		])