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>

target/tilegx/cpu.h

@@ -143,8 +143,6 @@ static inline TileGXCPU *tilegx_env_get_cpu(CPUTLGState *env)
     return container_of(env, TileGXCPU, env);
 }
 
-#define ENV_GET_CPU(e) CPU(tilegx_env_get_cpu(e))
-
 #define ENV_OFFSET offsetof(TileGXCPU, env)
 
 /* TILE-Gx memory attributes */