usertools: show hugepages on POWER systems

usertools: show hugepages on POWER systems

The IBM PowerNV systems include NUMA nodes that don't have associated
CPUs or hugepage memory.  Here is an example on an IBM AC922 system:

$ lscpu
...
NUMA node0 CPU(s):   0-63
NUMA node8 CPU(s):   64-127
NUMA node252 CPU(s):
...

$ numastat -m
...
                          Node 0          Node 8        Node 252
                 --------------- --------------- ---------------
MemTotal               126763.19       130785.06            0.00
MemFree                119513.38       125294.44            0.00
MemUsed                  7249.81         5490.62            0.00
...
HugePages_Total             4.00         1734.00            0.00
HugePages_Free              0.00            4.00            0.00
HugePages_Surp              4.00         1730.00            0.00
...

Modify dpdk-hugepages.py to test for the ../hugepages directory before
attempting to parse the hugepage entries.

Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>