ntp: fix build failure

This patch adds a patch to NTP to fix the following build failure,
using a workaround patch found on the Fedora bugzilla:

ntp_loopfilter.c: In function 'local_clock':
ntp_loopfilter.c:571: error: 'MOD_NANO' undeclared (first use in this function)
ntp_loopfilter.c:571: error: (Each undeclared identifier is reported only once
ntp_loopfilter.c:571: error: for each function it appears in.)
ntp_loopfilter.c: In function 'loop_config':
ntp_loopfilter.c:896: error: 'MOD_NANO' undeclared (first use in this function)

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