accel/tcg: Set can_do_io at at start of lookup_tb_ptr helper

accel/tcg: Set can_do_io at at start of lookup_tb_ptr helper

If a page table is in IO memory and lookup_tb_ptr probes
the TLB it can result in a page table walk for the instruction
fetch.  If this hits IO memory and io_prepare falsely assumes
it needs to do a TLB recompile.

Avoid that by setting can_do_io at the start of lookup_tb_ptr.

Link: https://lore.kernel.org/qemu-devel/CAFEAcA_a_AyQ=Epz3_+CheAT8Crsk9mOu894wbNW_FywamkZiw@mail.gmail.com/#t
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20240219173153.12114-2-Jonathan.Cameron@huawei.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>