ice: Check VF VSI Pointer Value in ice_vc_add_fdir_fltr()

As mentioned in the commit baeb705f ("ice: always check VF VSI
pointer values"), we need to perform a null pointer check on the return
value of ice_get_vf_vsi() before using it.

Fixes: 6ebbe97a ("ice: Add a per-VF limit on number of FDIR filters")
Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://patch.msgid.link/20250425222636.3188441-3-anthony.l.nguyen@intel.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>