ice: fix use-after-free in dynamic port cleanup

ice_dealloc_dynamic_port() uses dyn_port->vsi->idx to erase the dynamic
port from pf->dyn_ports. However, it frees the VSI before reading the
index for the erase, resulting in a use-after-free.

Follow the reverse of the allocation order in ice_alloc_dynamic_port()
by erasing the xarray entry before freeing the VSI.

Fixes: eda69d654c7e ("ice: add basic devlink subfunctions support")
Cc: stable@vger.kernel.org
Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
Reviewed-by: Marcin Szycik <marcin.szycik@linux.intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Patryk Holda <patryk.holda@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://patch.msgid.link/20260928230429.495442-3-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>