gallium/util: adapt util code to interface changes

gallium/util: adapt util code to interface changes

The util blit functions change their interface (apart from some rename) too
(in particular util_blit_pixels now also takes a pipe_resource as the src blit
argument instead of a surface, as it might just call resource_copy_region).
Maybe the blit util code might need a bit more cleanup, it still doesn't feel
very clean. In particular it seems that util_blit_pixels_tex should probably
disappear, and I think it would be great if the code called by drivers for
blitting (u_blitter.c, which isn't really touched by this change) could somehow
be merged with the u_blit code.