cpu: Replace ENV_GET_CPU with env_cpu

Now that we have both ArchCPU and CPUArchState, we can define
this generically instead of via macro in each target's cpu.h.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

hw/semihosting/console.c

@@ -40,7 +40,7 @@ int qemu_semihosting_log_out(const char *s, int len)
  */
 static GString *copy_user_string(CPUArchState *env, target_ulong addr, int len)
 {
-    CPUState *cpu = ENV_GET_CPU(env);
+    CPUState *cpu = env_cpu(env);
     GString *s = g_string_sized_new(len ? len : 128);
     uint8_t c;
     bool done;