counter: ti-eqep: remove unused struct member

Since commit 8817c2d0 ("counter: ti-eqep: Convert to counter_priv()
wrapper") the counter field in struct ti_eqep_cnt is not used anymore.
Remove it.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Judith Mendez <jm@ti.com>
Link: https://lore.kernel.org/r/20240609-ti-eqep-cleanup-v1-1-9d67939c763a@baylibre.com


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