clock: Remove old type-less time literals

Drop the s64 literals _ms, _ns, etc., from <drivers/clock.hh>.
Fix a few places which still use the old literals.

The std:chrono::duration version from <osv/clock.hh> remains -
but remember you need to "using namespace osv::clock::literals"
to use them.

Reviewed-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>