tcg/tci: Merge identical cases in generation (exchange opcodes)

tcg/tci: Merge identical cases in generation (exchange opcodes)

Use CASE_32_64 and CASE_64 to reduce ifdefs and merge
cases that are identical between 32-bit and 64-bit hosts.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210217202036.1724901-5-richard.henderson@linaro.org>
[PMD: Split patch as 2/5]
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210218232840.1760806-3-f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>