ACPI: GTDT: Correctly number platform devices for MMIO timers

ACPI: GTDT: Correctly number platform devices for MMIO timers

Use the actual timer counter instead of the watchdog counter.

Fixes: 5669d92f3efa ("ACPI: GTDT: Generate platform devices for MMIO timers")
Reported-by: Pavan Kondeti <pavan.kondeti@oss.qualcomm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Will Deacon <will@kernel.org>