kvm: x86: Remove obsolete SS.RPL/DPL aligment

This seems to date back to the days KVM didn't support real mode. The
check is no longer needed and, even worse, is corrupting the guest state
in case SS.RPL != DPL.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
