Fix naming confusion: number of symbol kallsyms is "num_kallsyms",

Fix naming confusion: number of symbol kallsyms is "num_kallsyms",
while number of symbols is "num_syms". It used to be "num_syms" and
"num_ksyms" respectively (ie the "k" was the wrong way around).

The previous naming was not just confusing, it had caused one actual
bug (ie the normal symbol code had used "num_syms", which was wrong
in the old confusing naming scheme).