Change qemuSetSchedularParameters to use AFFECT_CURRENT

Change qemuSetSchedularParameters to use AFFECT_CURRENT

When adding variants of parameter setting APIs which accepted
flags, the existing APIs were all adapted internally to pass
VIR_DOMAIN_AFFECT_CURRENT to the new API. The QEMU impl
qemuSetSchedularParameters was an exception, which instead
used VIR_DOMAIN_AFFECT_LIVE. Change this to match other
compatibility scenarios, so that calling

   virDomainSetSchedularParameters(dom, params, nparams);

Has the same semantics as

   virDomainSetSchedularParametersFlags(dom, params, nparams, 0);

And

   virDomainSetSchedularParametersFlags(dom, params, nparams, VIR_DOMAIN_AFFECT_CURRENT);

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>