meta/blit: Don't bind texture in _mesa_meta_bind_rb_as_tex_image

meta/blit: Don't bind texture in _mesa_meta_bind_rb_as_tex_image

All of the callers of _mesa_meta_bind_rb_as_tex_image call
_mesa_meta_setup_sampler shortly after.  _mesa_meta_setup_sampler also
binds the texture.  This is necessary because not all paths that lead to
_mesa_meta_setup_sampler some through _mesa_meta_bind_rb_as_tex_image.

Rename the function _mesa_meta_texture_object_from_renderbuffer to
reflect its true purpose.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>