i965/gen6+: Support 128 varying components.

i965/gen6+: Support 128 varying components.

GL 3.2 requires us to support 128 varying components for geometry
shader outputs and fragment shader inputs, and 64 varying components
otherwise.  But there's no hardware limitation that restricts us to 64
varying components, and core Mesa doesn't currently allow different
stages to have different maximum values, so just go ahead and enable
128 varying components for all stages.  This gets us better test
coverage anyway.

Even though we are only working on GL 3.2 support for gen7 right now,
gen6 also supports 128 varying components, so go ahead and switch it
on there too.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>