clk: mediatek: pllfh: Don't log error for missing fhctl node

Support for fhctl clocks in apmixedsys was introduced at a later point
and to this moment only one mt6795 based platform has a fhctl DT node
present. Therefore the fhctl support in apmixedsys should be seen as
optional and not cause an error when it is missing.

Change the message's log level to warning. The warning level is chosen
so that it will still alert the fact that fhctl support might be
unintentionally missing, but without implying that this is necessarily
an issue.

Even if the FHCTL DT nodes are added to all current platforms moving
forward, since those changes won't be backported, this ensures stable
kernel releases won't have live with this error.

Fixes: d7964de8 ("clk: mediatek: Add new clock driver to handle FHCTL hardware")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Link: https://lore.kernel.org/r/20240308-mtk-fhctl-no-node-error-v1-1-51e446eb149a@collabora.com


Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>