Make use of devm_clk_get_enabled() to replace devm_clk_get() and
clk_prepare_enable() for isfr and iahb clocks, and drop the now
unnecessary calls to clk_disable_unprepare().

Similarly, use devm_clk_get_optional_enabled() helper for cec clock,
which additionally allows to remove the -ENOENT test.

Moreover, the clock related members of struct dw_hdmi are not required
anymore, hence drop them.
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240813-dw-hdmi-simple-clk-v1-1-78d45cef02a9@collabora.com