Changes the address type of the guest memory read/write functions from
target_ulong to abi_ptr. (abi_ptr is currently typedef'd to target_ulong
but that will change in a following commit.) This will reduce the
coupling between accel/ and target/.

Note: Function pointers that point to cpu_[st|ld]*() in target/riscv and
target/rx are also updated in this commit.

Signed-off-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230807155706.9580-6-anjo@rev.ng>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>