ppc64_cpu: output to user if the requested number of cores are not brought online
ppc64_cpu: output to user if the requested number of cores are not brought online

Now that we check the return code from set_one_core, we should ensure
that the requested number of cores in --cores-on is achieved, or return
-1 intead. Also add a slightly verbose message in that case.

Signed-off-by: Nishanth Aravamudan <32d5d7104760c6969dbcc939b04e64f225673f91@linux.vnet.ibm.com>

shenki/powerpc-utils,shenki/powerpc-utils,shenki/powerpc-utils