counter: 104-quad-8: Add Signal polarity component

The 104-quad-8 driver provides support for Index signal polarity modes
via the "index_polarity" Signal component. This patch exposes the same
functionality through the more standard "polarity" Signal component.

Link: https://lore.kernel.org/r/01d00c21873159833035cb6775d0d0e8ad55f2ef.1664204990.git.william.gray@linaro.org/


Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/0bf840beee1665e9f04ea82368ecdde87c791a22.1664318353.git.william.gray@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>