nodeinfo: fix to parse present cpus rather than possible cpus

nodeinfo: fix to parse present cpus rather than possible cpus

This patch resolves a situation where a core is defective and is not
in the present mask during boot. Optionally a host can have empty sockets
could be brought online if the socket is added. In this case the present
mask contains the cpu's that are actually there in the sockets even though
they might be offline for some reason. This patch excludes the cpu's that
are offline because the socket is defective/empty by checking the present
mask before reading the cpu directory. Otherwise, the nodeinfo on such
hosts always displays wrong output which includes the defective/empty
sockets as set of offline cpu's.

Signed-off-by: Kothapally Madhu Pavan <kmp@linux.vnet.ibm.com>