etnaviv: don't do resolve-in-place without valid TS

etnaviv: don't do resolve-in-place without valid TS

GC3000 resolve-in-place assumes that the TS state is configured.
If it is not, this will result in MMU errors. This is especially
apparent when using glGenMipmaps().

Fixes: 78ade659569e ("etnaviv: Do GC3000 resolve-in-place when possible")
Cc: mesa-stable@lists.freedesktop.org
Signed-off-by: Wladimir J. van der Laan <laanwj@gmail.com>
Tested-by: Chris Healy <cphealy@gmail.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>