LU-6690 tests: start nfsserver service for SLES

LU-6690 tests: start nfsserver service for SLES

The NFS server service name in SLES distro is "nfsserver"
instead of "nfs". This patch fixes setup-nfs.sh to start
nfsserver service for SLES.

Test-Parameters: alwaysuploadlogs \
envdefinitions=EXCEPT=compilebench \
mdtfilesystemtype=ldiskfs mdsfilesystemtype=ldiskfs ostfilesystemtype=ldiskfs \
clientdistro=sles11sp3 ossdistro=sles11sp3 mdsdistro=sles11sp3 \
mdtcount=1 testlist=parallel-scale-nfsv3,parallel-scale-nfsv4

Test-Parameters: alwaysuploadlogs \
mdtfilesystemtype=ldiskfs mdsfilesystemtype=ldiskfs ostfilesystemtype=ldiskfs \
clientdistro=el6.6 ossdistro=el6.6 mdsdistro=el6.6 \
mdtcount=1 testlist=parallel-scale-nfsv3,parallel-scale-nfsv4

Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: Ifb200400c0fa072fee6f563431be0429e2c79890
Reviewed-on: http://review.whamcloud.com/15149
Reviewed-by: Wei Liu <wei3.liu@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Minh Diep <minh.diep@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>