kernel/vmem: fix vmem_tree_add()

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
kernel/paging: add paging_virt_to_phys()

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
kernel: allocate network buffers dynamically

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>