counter: ti-eqep: enable clock at probe

The TI eQEP clock is both a functional and interface clock. Since it is
required for the device to function, we should be enabling it at probe.

Up to now, we've just been lucky that the clock was enabled by something
else on the system already.

Fixes: f213729f

 ("counter: new TI eQEP driver")
Reviewed-by: Judith Mendez <jm@ti.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20240621-ti-eqep-enable-clock-v2-1-edd3421b54d4@baylibre.com
Signed-off-by: William Breathitt Gray <wbg@kernel.org>