gpsd: fixup various problems with Config.in

fix wrong configure symbol name for MTK.
remove default values from most of options and leave only
default y for NMEA protocol (90% of users will need this one)
and features for gpsd to reconfigure device.

Signed-off-by: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>