LU-12678 lnet: use init_wait() rather than init_waitqueue_entry()

LU-12678 lnet: use init_wait() rather than init_waitqueue_entry()

init_waitqueue_entry(foo, current)

is equivalent to

  init_wait(foo)

 So use the shorter version.

Change-Id: Ic63e99d75986211d9655a89f56721394c7b3abb6
Signed-off-by: Mr. NeilBrown <neilb@suse.de>
Reviewed-on: https://review.whamcloud.com/39295
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>