counter: Add microchip TCB capture counter

This drivers allows to use the capture mode of the Timer Counter Block
hardware block available in Microchip SoCs through the counter subsystem.

Two functions of the counter are supported for the moment: period
capture and quadrature decoder. The latter is only supported by the
SAMA5 series of SoCs.

For the period capture mode a basic setup has been chosen that will
reset the counter each time the period is actually reached. Of course
the device offers much more possibilities.

For quadrature mode, both channel 0 and 1 must be configured even if we
only capture the position (no revolution/rotation).

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>