PCI: brcmstb: Set new flags to avoid QOS "holes" on BCM2712D0

Set some flags present (and recommended) in 2712D0, but missing
(and harmless) in 2712C1. In particular, EN_QOS_UPDATE_TIMING_FIX
must be set to avoid spurious QOS=0 when the queue changes from
empty to non-empty, to make D0 match the existing C1 behaviour.

Not enabling "QOS forwarding", which still seems not to help.

Signed-off-by: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>