nir/spirv: Use the correct sources for CompareExchange on images
nir/spirv: Use the correct sources for CompareExchange on images

The CompareExchange operation has two "Memory Semantics" parameters instead
of one so the real arguments start at w[7] instead of w[6].

Signed-off-by: Jason Ekstrand <68c46a606457643eab92053c1c05574abb26f861@jlekstrand.net>
Cc: "12.0" <59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org>
Reviewed-by: Dave Airlie <f2295d84e358395675bc8031be58672073ae065e@redhat.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler