etnaviv: increment correct seqno for external resources

etnaviv: increment correct seqno for external resources

If we import a dma-buf with a sampler/pixel pipe incompatible modifier,
the imported buffer will end up in an external resource view. As
resource_changed signals the change of the imported resource, we need
to update the external view seqno, instead of the base resource seqno.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Wladimir J. van der Laan <laanwj@gmail.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>