Further fixed PHP Warning in proximity filter when field is not "field_geofield"

- Issue #3299818 by jessehs: PHP Warning in proximity filter when field is not "field_geofield"'
- Issue #3299813: Undefined array key "field_geofield_proximity_op" when using proximity filter on (at least) non node entity (+1 squashed commit)
Squashed commits:
[1923421] Further fixed PHP Warning in proximity filter when field is not "field_geofield"
- Issue #3299818 by jessehs: PHP Warning in proximity filter when field is not "field_geofield"'
- Issue #3299813: Undefined array key "field_geofield_proximity_op" when using proximity filter on (at least) non node entity