counter:ti-eqep: remove floor

The hardware doesn't support this. QPOSINIT is an initialization value
that is triggered by other things. When the counter overflows, it
always wraps around to zero.

Fixes: f213729f

 "counter: new TI eQEP driver"
Signed-off-by: David Lechner <david@lechnology.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/20201214000927.1793062-1-david@lechnology.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>