input: atmel_mxt_ts: Support runtime selection of config data

Add support for dynamic configuration data update if the target can
support more than one Atmel chip. Platform data contains an array of
supported config data along with family ID, variant ID and firmware
version. Driver searches for matching family ID, variant ID and
firmware version, and uses the corresponding config data to program.

Change-Id: I684da4bdef56a3445acab3bb8fe47dd5279bebe5
Signed-off-by: Jing Lin <jinglin@codeaurora.org>