tcg: Remove TCGV_UNUSED* and TCGV_IS_UNUSED*

These are now trivial sets and tests against NULL.  Unwrap.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/target/cris/translate.c b/target/cris/translate.c
index 2831419..74822ed 100644
--- a/target/cris/translate.c
+++ b/target/cris/translate.c
@@ -2603,7 +2603,7 @@
         tcg_gen_addi_tl(addr, cpu_R[dc->op1], i * 8);
         gen_load(dc, tmp32, addr, 4, 0);
     } else {
-        TCGV_UNUSED(tmp32);
+        tmp32 = NULL;
     }
     tcg_temp_free(addr);