i965: Require a UBO offset alignment of 32 bytes.

i965: Require a UBO offset alignment of 32 bytes.

Soon, we're going to start providing UBO data to shaders as push
constants, rather than requiring them to issue pull loads.  The
3DSTATE_CONSTANT_* commands require 32 byte aligned pointers.

So, we need to increase this from 16 to 32.

Reviewed-by: Matt Turner <mattst88@gmail.com>