platform/x86: int3472: Check for adev == NULL

In the Linux kernel, the following vulnerability has been resolved: platform/x86: int3472: Check for adev == NULL Not all devices have an ACPI companion fwnode, so adev might be NULL. This can e.g. (theoretically) happen when a user manually binds one of the int3472 drivers to another i2c/platform device through sysfs. Add a check for adev not being set and return -ENODEV in that case to avoid a possible NULL pointer deref in skl_int3472_get_acpi_buffer().