i915: Fix NPOT compressed textures on 915.

We were failing at rounding, misplacing the non-baselevels.  Fixes:
3DFX_texture_compression_FXT1/fbo-generate-mipmaps
ARB_texture_compression/fbo-generate-mipmaps
EXT_texture_compression_s3tc/fbo-generate-mipmaps

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/mesa/drivers/dri/i915/i915_tex_layout.c

@@ -219,9 +219,9 @@ i915_miptree_layout_2d(struct intel_context *intel,
 				   width, height, 1);
 
       if (mt->compressed)
-	 img_height = MAX2(1, height / 4);
+	 img_height = ALIGN(height, 4) / 4;
       else
-	 img_height = (MAX2(2, height) + 1) & ~1;
+	 img_height = ALIGN(height, 2);
 
       mt->total_height += img_height;