Parsing a timeout value (specified in milliseconds) into an internal
timeout value measured in timer ticks is a common operation. Provide
a parse_timeout() value to carry out this conversion automatically.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add "sync" command (loosely based on the Unix "sync"), which will wait
for any pending operations to complete.
Signed-off-by: Michael Brown <mcb30@ipxe.org>