i965/barrier: Do the correct flushes for framebuffer access

i965/barrier: Do the correct flushes for framebuffer access

Framebuffer access includes framebuffer reads so we need to invalidate
the texture cache.  We do not, however, need to flush the depth cache
because you cannot do bind a depth texture as an image.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>