Counter width of GIC is configurable and can be read from a
register.

Use width value from the register for sched_clock.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Link: https://lore.kernel.org/r/20240612-mips-clks-v2-7-a57e6f49f3db@flygoat.comSigned-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>