Input: introduce tsc2005 driver

Discussions:

http://www.mail-archive.com/linux-omap@vger.kernel.org/msg26748.html

Introduce a driver for the Texas Instruments TSC2005 touchscreen
controller (http://focus.ti.com/docs/prod/folders/print/tsc2005.html

).

The patch is based on a driver by Lauri Leukkunen, with modifications
by David Brownell, Phil Carmody, Imre Deak, Hiroshi DOYU, Ari Kauppi,
Tony Lindgren, Jarkko Nikula, Eero Nurkkala and Roman Tereshonkov.

Signed-off-by: Lauri Leukkunen <lauri.leukkunen@nokia.com>
[aaro.koskinen@nokia.com: patch description, rebasing & cleanup]
Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
[ext-srikar.1.bhavanarayana@nokia.com: various fixes]
Signed-off-by: Srikar <ext-srikar.1.bhavanarayana@nokia.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>