i965/vec4: Use byte offsets for UBO pulls on Sandy Bridge

i965/vec4: Use byte offsets for UBO pulls on Sandy Bridge

Previously, the VS_OPCODE_PULL_CONSTANT_LOAD opcode operated on
vec4-aligned byte offsets on Iron Lake and below and worked in terms of
vec4 offsets on Sandy Bridge.  On Ivy Bridge, we add a new *LOAD_GEN7
variant which works in terms of vec4s.  We're about to change the GEN7
version to work in terms of bytes, so this is a nice unification.

Cc: "11.0" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>