clk: imx: Add imx8m_clk_hw_composite_flags macro

In order to set custom flags to imx8m_clk_hw_composite,
split it off into a separate macro which can accept additional
flags.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Link: https://lore.kernel.org/r/20230323230127.120883-3-aford173@gmail.com