counter: microchip-tcb-capture: Constify mchp_tc_ops

counter: microchip-tcb-capture: Constify mchp_tc_ops

The only usage of mchp_tc_ops is to assign its address to the ops field
in the counter_device struct which is a const pointer. Make it const to
allow the compiler to put it in read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/20200922201941.41328-1-rikard.falkeborn@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>