ASoC: dt-bindings: wlf,wm8782: Add wlf,fsampen property

The WM8782 can safely support rates higher than 48kHz by changing the
value of the FSAMPEN pin.

Allow specifying the FSAMPEN pin value in the device tree.

Signed-off-by: John Watts <contact@jookia.org>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230918131532.2257615-4-contact@jookia.org
Signed-off-by: Mark Brown <broonie@kernel.org>