llvmpipe: simplify buffer allocation logic.

Now with buffer formats clarification don't need all that logic any longer.
(Note that it never would have worked in any case, because blockwidth and
blockheight were swapped any allocation with multi-byte format would have
had zero size.)

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

src/gallium/drivers/llvmpipe/lp_texture.c

@@ -311,13 +311,11 @@ llvmpipe_resource_create(struct pipe_screen *_screen,
    }
    else {
       /* other data (vertex buffer, const buffer, etc) */
-      const enum pipe_format format = templat->format;
-      const uint w = templat->width0 / util_format_get_blockheight(format);
-      /* XXX buffers should only have one dimension, those values should be 1 */
-      const uint h = templat->height0 / util_format_get_blockwidth(format);
-      const uint d = templat->depth0;
-      const uint bpp = util_format_get_blocksize(format);
-      const uint bytes = w * h * d * bpp;
+      const uint bytes = templat->width0;
+      assert(util_format_get_blocksize(templat->format) == 1);
+      assert(templat->height0 == 1);
+      assert(templat->depth0 == 1);
+      assert(templat->last_level == 0);
       lpr->data = align_malloc(bytes, 16);
       if (!lpr->data)
          goto fail;