mlxsw: core_thermal: Use exact name of cooling devices for binding

Modular system supports additional cooling devices "mlxreg_fan1",
"mlxreg_fan2", etcetera. Thermal zones in "mlxsw" driver should be
bound to the same device as before called "mlxreg_fan". Used exact
match for cooling device name to avoid binding to new additional
cooling devices.

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>