pwm: mediatek: Handle hardware enable and clock enable separately

Stop handling the clocks in pwm_mediatek_enable() and
pwm_mediatek_disable(). This is a preparing change for the next commit
that requires that clocks and the enable bit are handled separately.

Also move these two functions a bit further up in the source file to
make them usable in pwm_mediatek_config(), which is needed in the next
commit, too.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/55c94fe2917ece152ee1e998f4675642a7716f13.1753717973.git.u.kleine-koenig@baylibre.com


Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>