counter: 104-quad-8: Refactor to buffer states for CMR, IOR, and IDR

The 104-quad-8 driver buffers the device configuration states
separately, however each device has only three control registers: CMR,
IOR, and IDR. Refactoring to buffer the states of these control
registers rather than each configuration separately results in succinct
code that more closely matches what is happening on the device.

Link: https://lore.kernel.org/r/48071415aed43ecdd8595174191b0d906205a9e3.1681753140.git.william.gray@linaro.org/Signed-off-by: William Breathitt Gray <william.gray@linaro.org>