platform/x86: dell-wmi: Label driver as handling notifications

This driver serves the purpose of responding to WMI based notifications
from the DELL_EVENT_GUID (9DBB5994-A997-11DA-B012-B622A1EF5492).
Other GUIDs will be handled by separate drivers.

Update the language used by this driver to avoid future confusion.

Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>