stmpe-ts: Fix inverted pressure, empty datasets and IRQ flag

This patch adresses 3 issues:
1. Report increased pressure with increasing numbers
2. Skip empty datasets
   stmpe_work() resets the FIFO, and this can happen during an interrupt
3. Reset the touch controller part if the FIFO_TH flag is not cleared.
   If the flag is not cleared, the result is a nonresponsive touchpanel.
   The flag has to be cleared for the controller to generate an interrupt.
   There are 3 people reporting this on the Adafruit PiTFT display
   Links:
   http://forums.adafruit.com/viewtopic.php?f=50&t=51432
   https://github.com/notro/fbtft/issues/82
arm: configs: Add more panels to adafruit_defconfig

Add more LCD panels to the default list of modules to build.
fbtft: Update submodule ref

The newer fbtft driver includes support for more panels.  Include the
newer ref as part of the submodule.