LU-9118 o2iblnd: handle MOFED libcfs time api collision

LU-9118 o2iblnd: handle MOFED libcfs time api collision

Both libcfs and the MOFED 4 stack define
ktime_get_real_ns() for platforms that lack it.
The solution is to reverse the logic of testing
for ktime_get_real_ns() done by lustre. This way
we avoid the HAVE_KTIME_GET_REAL_NS collision.
Also to ensure older platforms with an older OFED
stack still will build only turn off NEED_KTIME_GET_REAL_NS
set by libcfs in o2iblnd.h when the OFED stack
has defined LINUX_3_17_COMPAT_H. The compat-3.17.h
OFED header is where ktime_get_real_ns() gets defined
when its lacking on the native platform.

Test-Parameters: trivial

Change-Id: I44966f22cfbb6138fa7bc3fa47148a6f0a94ebd4
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/25564
Tested-by: Jenkins
Reviewed-by: Olaf Weber <olaf@sgi.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>