vfs: Add wrappers for basic vfs operations

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
kernel/pmem: Fix pmem_block::flags

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
kernel/vmem: Fix root area insertion

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
kernel/vm: Reduce number of early pages to 1

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
arch/x86_64: Fix build

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