asahi: Fix texture atomics on G13X

Add the magic helper memory barriers, and add one to the texture atomics barrier.

This seems to be required on G13X, otherwise KHR-GLES31.core.texture_buffer.texture_buffer_atomic_functions fails. Found via guesswork, and currently reusing the needs_g13x_coherency logic on principle (since that is related to atomics). Tested on G13D, Janne confirmed this is also needed on G13C,. G14C is not affected (and does not enable this), which leaves G14D as the only untested branch (where we enable the barrier as the only 2-die G14 device). Given that the helper program runs this instruction even on G13G, it's probably harmless to add even if unnecessary, so this logic should be at least safe.

Signed-off-by: Asahi Lina lina@asahilina.net