livepatch: add transition notices

Log a few kernel debug messages at the beginning of the following livepatch
transition functions:

  klp_complete_transition()
  klp_cancel_transition()
  klp_init_transition()
  klp_reverse_transition()

Also update the log notice message in klp_start_transition() for similar
verbiage as the above messages.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>