dt-bindings: net: ti: icssg_prueth: Add documentation for PA_STATS support

Add documentation for ti,pa-stats property which is syscon regmap for
PA_STATS registers. This will be used to dump statistics maintained by
ICSSG firmware.

Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240529115225.630535-1-danishanwar@ti.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>