platform/x86: dual_accel_detect: Use the new i2c_acpi_client_count() helper

Use the new i2c_acpi_client_count() helper, this
results in a nice cleanup.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210803160044.158802-3-hdegoede@redhat.com