clk: mediatek: fhctl: Add support for older fhctl register layout

clk: mediatek: fhctl: Add support for older fhctl register layout

The Frequency Hopping Controller (FHCTL) seems to have different
versions, as it has a slightly different register layout on some
older SoCs like MT6795, MT8173, MT8183 (and others).

This driver is indeed compatible with at least some of those older
IP revisions, so all we need to do is to add a way to select the
right register layout at registration time.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230206100105.861720-2-angelogioacchino.delregno@collabora.com
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>