tcg: don't abuse TCG type in tcg_gen_trunc_shr_i64_i32

The tcg_gen_trunc_shr_i64_i32 function takes a 64-bit argument and
returns a 32-bit value. Directly call tcg_gen_op3 with the correct
types instead of calling tcg_gen_op3i_i32 and abusing the TCG types.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>