target/microblaze: Have compute_ldst_addr_type[ab] return TCGv_i32

target/microblaze: Have compute_ldst_addr_type[ab] return TCGv_i32

Both compute_ldst_addr_typea() and compute_ldst_addr_typeb()
bodies use a TCGv_i32, so return the same type.

Suggested-by: Anton Johansson <anjo@rev.ng>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20251015180115.97493-6-philmd@linaro.org>