tools/livepatch: Remove pointless retry loop

tools/livepatch: Remove pointless retry loop

The default timeout in the hypervisor for a livepatch operation is 30 ms,
but xen-livepatch currently waits for up to 30 seconds for the operation
to complete. Instead, remove the retry loop and simply wait for 2 * 30 ms
for the operation to complete. The extra period is to account for the
time to actually start the operation.

Furthermore, have xen-livepatch set the hypervisor timeout rather than
relying on the hypervisor default since the tool doesn't know how long
it will be. Use nanosleep rather than usleep since usleep has been
removed from POSIX.1-2008.

Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>