input: synaptics_i2c_rmi: duplicated_filter to throttle touch events

Create multitouch threshold to prevent event hub from being flooded.
This attempts to (partially) address Android issue #7836:
http://code.google.com/p/android/issues/detail?id=7836

Depends on CONFIG_TOUCHSCREEN_DUPLICATED_FILTER=y

Originally authored by HTC for their Hero 2.6.29 kernel, ported to
kernel-hero by netarchy/ninpo, adapted to .34 by kernelzilla.

Conflicts:
	drivers/input/touchscreen/Kconfig

Change-Id: Id4cbdcd8093714d399dc09a94614028acf6fc76e

Conflicts:
	drivers/input/touchscreen/Kconfig