mlxsw: core_hwmon: Fix variable names for hwmon attributes

Replace all local variables 'mlwsw_hwmon_attr' by 'mlxsw_hwmon_attr'.
All variable prefixes should start with 'mlxsw' according to the naming
convention, so 'mlwsw' is changed to 'mlxsw'.

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