counter: ti-eqep: implement over/underflow events

This adds support to the TI eQEP counter driver for subscribing to
overflow and underflow events using the counter chrdev interface.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20240609-counter-ti-eqep-over-under-events-v1-1-74fe1632f5ab@baylibre.com


Signed-off-by: William Breathitt Gray <wbg@kernel.org>