i965: use L3 data cache for SSBOs

i965: use L3 data cache for SSBOs

Anv programs the hardware to use L3 data cache if we use either SSBOs or
images in the shaders, we can program i965 the same way.

gl_shader_program has a bit of a confusing named field with
'NumAtomicBuffers'. It doesn't tell how many buffers are accessed by the
shader in an atomic way but instead the number of atomic counters
manipulated by the shader.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>