package/gpsd: fix BR2_PACKAGE_GPSD_MAX_{CLIENT, DEV} options

limited_max_clients and limited_max_devices have been renamed in 3.12
as max_clients and max_devices, respectively.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau.dev@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>