mlxsw: core_thermal: Remove obsolete API for query resource

Remove obsolete API mlxsw_core_res_query_enabled(), which is only
relevant for end-of-life SwitchX-2 ASICs. Support for these ASICs was
removed in commit b0d80c01 ("mlxsw: Remove Mellanox SwitchX-2 ASIC
support").

Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>