target/arm: Drop define_one_arm_cp_reg_with_opaque

target/arm: Drop define_one_arm_cp_reg_with_opaque

The last use of this interface was removed in 603bc048a27f
("hw/arm: Remove pxa2xx_pic").  As the comment in gicv3
stated, keeping pointer references to cpregs has SMP issues,
so avoid future temptation by removing the interface.

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>