libxl/vcpuset: Remove useless limit on max_vcpus.

libxl/vcpuset: Remove useless limit on max_vcpus.

The check is superflous. If the 'max_vcpus' (argument
value) is greater than  pCPU and --ignore-host has not
been supplied we would print an warning and return
and not call this code.

If the --ignore-host parameter had been used we would
never end up in this condition and enforce 'max_vcpus'.

The only time it would be invoked is if max_vcpus < host_cpu
in which case it would set max_vcpus to max_vcpus.

In short - it is dead code.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>