Fixes echo_client and echo_server samples.
Fixes compile error:
...
src/built-in.o: In function `fdrm_k64f_cc2520_pinmux_setup':
samples/net/echo_client/src/../../common/cc2520_frdm_k64f.c:93:
undefined reference to `_fsl_k64_set_pin'
samples/net/echo_client/src/../../common/cc2520_frdm_k64f.c:93:
undefined reference to `_fsl_k64_set_pin'
samples/net/echo_client/src/../../common/cc2520_frdm_k64f.c:93:
undefined reference to `_fsl_k64_set_pin'
...
Change-Id: I590f88f6bd083a30deea77fa860f001a3a55b278
Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>