nvmet-fcloop: Check remoteport port_state before calling done callback

In the Linux kernel, the following vulnerability has been resolved:

nvmet-fcloop: Check remoteport port_state before calling done callback

In nvme_fc_handle_ls_rqst_work, the lsrsp->done callback is only set when
remoteport->port_state is FC_OBJSTATE_ONLINE. Otherwise, the
nvme_fc_xmt_ls_rsp's LLDD call to lport->ops->xmt_ls_rsp is expected to
fail and the nvme-fc transport layer itself will directly call
nvme_fc_xmt_ls_rsp_free instead of relying on LLDD's done callback to free
the lsrsp resources.

Update the fcloop_t2h_xmt_ls_rsp routine to check remoteport->port_state.
If online, then lsrsp->done callback will free the lsrsp. Else, return
-ENODEV to signal the nvme-fc transport to handle freeing lsrsp.