uap8xxx: Clean up device identifiers table

- Use the SDIO_DEVICE_ID_MARVELL_LIBERTAS defined by the kernel headers,
	removing the local definition.
- Add the SDIO_DEVICE_ID_MARVELL_8688WLAN device. At least the SD8688
	present in the Dreamplug revision with model number 003-DS2001 is known
	to report this identifier.
- Use a name for the table more coherent with what the rest of the drivers
	in the kernel do.