ARM: imx_v6_v7_defconfig: Select max11801_ts touchscreen driver

Select CONFIG_TOUCHSCREEN_MAX11801 so that we can have touchscreen
funtionality by default on Engicam i.CoreM6 Quad boards.

Cc: Matteo Lisi <matteo.lisi@engicam.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>