gdb: remove tracepoint_probe_create_sals_from_location_spec

The tracepoint_probe_create_sals_from_location_spec function just
forwards all its arguments to
bkpt_probe_create_sals_from_location_spec, and is only used in one
place.

Lets delete tracepoint_probe_create_sals_from_location_spec and
replace it with bkpt_probe_create_sals_from_location_spec.

There should be no user visible changes after this commit.