accel/tcg: Always require can_do_io

Require i/o as the last insn of a TranslationBlock always,
not only with icount.  This is required for i/o that alters
the address space, such as a pci config space write.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1866


Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>