LU-9859 libcfs: discard libcfs_prim.h

LU-9859 libcfs: discard libcfs_prim.h

This file no longer contains enough content
to justify a separate file.  So merge with
libcfs.h.

Linux-commit: 7673fd6b6af0c234e8ed5ec94c4da083b2f7d354

Change-Id: I4f486f0356f14e564032ed22e2e439fe4e65942c
Test-Parameters: trivial
Signed-off-by: Mr. NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-on: https://review.whamcloud.com/38673
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Gian-Carlo DeFazio <defazio1@llnl.gov>
Reviewed-by: Oleg Drokin <green@whamcloud.com>