bdflush.2, get_robust_list.2, kexec_load.2, madvise.2, mmap.2, mount.2, prctl.2,...

bdflush.2, get_robust_list.2, kexec_load.2, madvise.2, mmap.2, mount.2, prctl.2, query_module.2, rt_sigqueueinfo.2, shmget.2, sigaction.2, syscalls.2, umount.2, malloc.3, hpsa.4, initrd.4, proc.5, bootparam.7, icmp.7, netlink.7, signal.7: Global fix: use "Linux kernel source" consistently

Rather than "kernel source".

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>