mlxsw: core_linecards: Fix double memory deallocation in case of invalid INI file

In case of invalid INI file mlxsw_linecard_types_init() deallocates memory
but doesn't reset pointer to NULL and returns 0. In case of any error
occurred after mlxsw_linecard_types_init() call, mlxsw_linecards_init()
calls mlxsw_linecard_types_fini() which performs memory deallocation again.

Add pointer reset to NULL.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: b217127e

 ("mlxsw: core_linecards: Add line card objects and implement provisioning")
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Link: https://patch.msgid.link/20240703203251.8871-1-amishin@t-argos.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>