In case of page flip there is no need to iterate over all display unit
in the function "vmw_kms_helper_dirty". If crtc is available then
dirty commands is performed on that crtc only.
Signed-off-by: Deepak Rawat <drawat@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>