defconfig: drivers for EETI Egalax touchscreens (and likely others)

Alex got the EETI touchscreen to work with the BB, but had to rebuild
the evdev driver, which is why it's a module now

Also enable some other drivers which might make sense with USB touchscreens

Some userland work will be needed too to get things going (details forthcoming, but as a start):

We need to rebuild the evdev driver:

 mkdir evdev
 cd evdev/
 apt-get source xserver-xorg-input-evdev
 sudo apt-get build-dep xserver-xorg-input-evdev
 cd xserver-xorg-input-evdev-2.7.0/
 sudo apt-get install devscripts
 debuild -us -uc
 # now install the resulting .deb (../xserver-xorg-input-evdev_2.7.0-1_armhf.deb  for me)

assure these modules are loaded:
evdev
hid-multitouch

xinput_calibrator came from
http://www.freedesktop.org/wiki/Software/xinput_calibrator/
git clone https://github.com/tias/xinput_calibrator
cd xinput_calibrator
make
sudo make install

xinput_calibrator --list
xinput_calibrator --device <device_id>