input: ft5x06_ts: remove proximity sensor support

remove psensor support as the linux/sensors.h file is not yet merged
in msm-3.18 kernel.

Change-Id: I6d46b35938b7420072f9245ffa27bb59f28d5e03
Signed-off-by: Sudhakar Manapati <smanap@codeaurora.org>