Console validation is currently being done by qemuBuildConsoleCommandLine().
This patch moves it to a new qemuDomainDefValidateConsole() function. This
new function is then called by qemuDomainDefValidate(), validating the
console in domain define time.
Reviewed-by: NCole Robinson <crobinso@redhat.com>
Signed-off-by: NDaniel Henrique Barboza <danielhb413@gmail.com>