gpsd: remove option to enable latency measurement capabilities

It currently fails to build with:

libgpsd_core.c: In function 'gpsd_poll':
libgpsd_core.c:881: error: 'const struct gps_type_t' has no member named 'min_cycle'
libgpsd_core.c:884: error: 'const struct gps_type_t' has no member named 'min_cycle'

and is probably not a very important feature for normal users of gpsd.

The build problem has been reported to the gpsd-users mailing list.

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