staging: lustre: remove some unneeded cflags

The lnet code did not even need the cflags setting in the Makefile, so
remove it, as it is not doing anything at all.

Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: hpdd-discuss <hpdd-discuss@lists.01.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>