asus-acpi: Remove redundant NULL checks

asus-acpi: Remove redundant NULL checks

The acpi device callbacks add, start, remove, suspend and resume can
never be called with a NULL acpi_device. Each callsite in acpi/scan.c
has to dereference the device in order to get the ops structure, e.g.

    struct acpi_device *acpi_dev = to_acpi_device(dev);
    struct acpi_driver *acpi_drv = acpi_dev->driver;

    if (acpi_drv && acpi_drv->ops.suspend)
        return acpi_drv->ops.suspend(acpi_dev, state);

Remove all checks for acpi_dev == NULL within these callbacks.

Also remove the checks for acpi_driver_data(acpi_dev) == NULL. None of
these checks could fail unless the driver does something strange
(which none of them do), the acpi core did something terribly wrong,
or we have a memory corruption issue. If this does happen then it's
best to dereference the pointer and crash noisily.

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Len Brown <len.brown@intel.com>