LU-10467 llite: clean up pcc_layout_wait()

LU-10467 llite: clean up pcc_layout_wait()

pcc_layout_wait() contains a pointless while loop (and an unnecessary
blank line) and is a trivial function that is only called once.

So move the code into __pcc_layout_invalidate(), remove the while
loop, and generally tidy up.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I4a7c721a562682906dec4996bfbdad03e26a01dd
Reviewed-on: https://review.whamcloud.com/38403
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Yingjin Qian <qian@ddn.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>