cpuinfo.h - remove some now unrelated comment lines

Signed-off-by: Davide Madrisan <davide.madrisan@gmail.com>
meminfo lib - make the functino 'get_vmem_pagesize' private

Signed-off-by: Davide Madrisan <davide.madrisan@gmail.com>
meminfo,vminfo libs - #undef the macros when no more required in the remaining code

Signed-off-by: Davide Madrisan <davide.madrisan@gmail.com>