target/arm: fix TCG temp leak in aarch64 rev16

Fix a TCG temporary leak in the new aarch64 rev16 handling.
Signed-off-by: NEmilio G. Cota <cota@braap.org>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

target/arm/translate-a64.c

@@ -4051,6 +4051,7 @@ static void handle_rev16(DisasContext *s, unsigned int sf,
     tcg_gen_shli_i64(tcg_rd, tcg_rd, 8);
     tcg_gen_or_i64(tcg_rd, tcg_rd, tcg_tmp);
 
+    tcg_temp_free_i64(mask);
     tcg_temp_free_i64(tcg_tmp);
 }