The only allowed channel state changes are those that change
the channel state into a state with a higher numerical value.
This allows to merge the functions srpt_set_ch_state() and
srpt_test_and_set_ch_state() into a single function.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagig@mellanox.com> Cc: Alex Estrin <alex.estrin@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com>