i965: Implement the actual tables for texture alignment units [v2]

i965: Implement the actual tables for texture alignment units [v2]

I implemented functions for horizontal/vertical alignment units separately
because I find it easier to read that way...especially with all the
corner-cases.

[chad] Corrected the vertical alignment calculation by checking for
depthstencil formats.

v2:
   - Fix typos in intel_horizontal_texture_alignment_unit():
     s/height/width/ and s/VALIGN/HALIGN.
   - Remove special case for compressed formats in
     intel_get_texture_alignment unit(). Compressed formats are already
     handled in the halign and valign functions.
   - Replace check ``_mesa_is_depth_format(...) ||
     _mesa_is_depthstencil_format(...)`` with explcitit checks against
     GL_DEPTH_COMPONENT and GL_DEPTH_STENCIL.

Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>