[multipathd] make clear in the logs what triggered an action

[multipathd] make clear in the logs what triggered an action

Nov 24 17:37:58 | mpath0: event checker started
Nov 24 17:37:58 | mpath1: event checker started
Nov 24 17:37:58 | path checkers start up
Nov 24 17:38:08 | sdb: add path (uevent)
Nov 24 17:38:08 | 8:16: ownership set to mpath0
Nov 24 17:38:08 | sdc: add path (uevent)
Nov 24 17:38:08 | 8:32: ownership set to mpath1
Nov 24 17:38:23 | mpath1: switch to path group #1
Nov 24 17:39:21 | mpath1: switch to path group #2 (operator)
Nov 24 17:39:36 | mpath1: switch to path group #1
Nov 24 17:39:39 | mpath0: switch to path group #2
Nov 24 17:39:42 | sdb: remove path (operator)
Nov 24 17:39:47 | mpath1: switch to path group #2
Nov 24 17:40:15 | mpath1: switch to path group #1
Nov 24 17:40:50 | sdb: remove path (uevent)
Nov 24 17:40:50 | sdb: spurious uevent, path not in pathvec
Nov 24 17:40:50 | uevent trigger error
Nov 24 17:41:03 | sdb: add path (uevent)
Nov 24 17:41:04 | 8:16: ownership set to mpath0