mesa/st/glsl_to_tgsi: remove now unneeded assert.

With the implementation of the tracking of the registers used in reladdr
asserting that a driver calling merge_register() uses the address register
is no longer needed.

Reviewed-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Gert Wollny <gw.fossdev@gmail.com>

src/mesa/state_tracker/st_glsl_to_tgsi.cpp

@@ -5310,7 +5310,6 @@ glsl_to_tgsi_visitor::merge_two_dsts(void)
 void
 glsl_to_tgsi_visitor::merge_registers(void)
 {
-   assert(need_uarl);
    struct lifetime *lifetimes =
          rzalloc_array(mem_ctx, struct lifetime, this->next_temp);