Input: elantech - fix for newer hardware versions (v7)
* Fix version recognition in elantech_set_properties
The new hardware reports itself as v7 but the packets'
structure is unaltered.
* Fix packet type recognition in elantech_packet_check_v4
The bitmask used for v6 is too wide, only the last three bits of
the third byte in a packet (packet[3] & 0x03) are actually used to
distinguish between packet types.
Starting from v7, additional information (to be interpreted) is
stored in the remaining bits (packets[3] & 0x1c).
In addition, the value stored in (packet[0] & 0x0c) is no longer
a constant but contains additional information yet to be deciphered.
This change should be backwards compatible with v6 hardware.