rockchip: clk: fix wrong CONFIG_IS_ENABLED handling

CONFIG_IS_ENABLED() needs the config name like used in Kconfig, so
without the leading CONFIG_. The clock drivers all wrongly check for
CONFIG_RESET_ROCKCHIP, fix that

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>