Input: eeti_ts - use get_unaligned_be16() to retrieve data

Instead of manually converting big endian data on wire into host
endianness, let's use helpers to do that for us. It might save us
a few cycles if host endianness matches what's on wire.

Reviewed-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>