eeepc-laptop: revise names

eeepc-laptop now does a lot more than just hotkeys.  Replace the "hotk"
names used throughout the driver with some slightly more appropriate
names.  The actual strings used in kernel messages and sysfs are left
unchanged.

e.g.
	EEEPC_HOTK_FILE  -> EEEPC_LAPTOP_FILE
	EEEPC_HOTK_HID   -> EEEPC_ACPI_HID

	eeepc_hotk_notify -> eeepc_acpi_notify
	struct eeepc_hotk -> struct eeepc_laptop
	ehotk             -> eeepc

I'm about to refactor the entire driver to remove the global "ehotk"
variable, and I don't wish to add "struct eeepc_hotk *ehotk" to
functions which have nothing to do with hotkeys.

Also
 - fix the name of "eepc_get_entry_by_keycode()"
 - remove the unused definition of NOTIFY_WLAN_ON.

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