numa: forbid '-numa node, mem' for 5.1 and newer machine types

numa: forbid '-numa node, mem' for 5.1 and newer machine types

Deprecation period is run out and it's a time to flip the switch
introduced by cd5ff8333a.  Disable legacy option for new machine
types (since 5.1) and amend documentation.

'-numa node,memdev' shall be used instead of disabled option
with new machine types.

Signed-off-by: Igor Mammedov <[email protected]>
Reviewed-by: Michal Privoznik <[email protected]>
Reviewed-by: Michael S. Tsirkin <[email protected]>
Reviewed-by: Greg Kurz <[email protected]>
Message-Id: <20200609135635[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>