Fix a TCG temporary leak when translating CACHE opcode.

Fixes: 0d74a222 ("make ITC Configuration Tags accessible to the CPU")
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210406202857.1440744-1-f4bug@amsat.org>