rockchip: include asm/io.h directly in asm/arch-rockchip/hardware.h

The different macros use writel which is defined in asm/io.h, so let's
include the header so users of hardware.h do not need to include
asm/io.h as well.

While at it, remove asm/io.h includes wherever
asm/arch-rockchip/hardware.h is included already.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>