scsi_transport_srp: Fix a race condition

Avoid canceling the fast_fail_io and/or dev_loss timers concurrently
with srp_start_tl_fail_timers().
scsi_transport_srp: Fix a race condition

Avoid invoking ping_async() concurrently with reconnect().
IB/srp: Improve ping mechanism debug logging

Avoid negative ping response debug logs due to latest_ping_response
being initialized to zero instead of the current time. This change
only affects the log output and not the communication timeout
detection algorithm.
scsi_transport_srp: Protect delay_interval and ping_interval modifications

Avoid that changing these sysfs parameters can race with the code
for handling transport layer errors and/or the code for reconnecting.
scsi_transport_srp: Rename "rport_state" into "state"
scsi_transport_srp: Do not lock the scan_mutex while reconnecting

Changing the state of all SCSI devices into SDEV_BLOCK is sufficient.
IB/srp: Remove two sysfs attributes
IB/srp: Bump version to 1.4.1