input: touchscreen: modify report event according to MT protocol B

Multi-touch(MT) protocol B use input_mt_report_slot_state()
instead of send ABS_MT_TRACKING_ID event directly, so modify
the driver to follow the protocol and remove redundant protocol
A code.

This patch is propagated from msm-3.10 kernel
(commit: 071f211230a1e78c91c6719c518adefa3b7e453b
input: touchscreen: modify report event according to MT protocol B)

Change-Id: I542e61fabaaa04fcf5fb7e454e10599511f18e39
Signed-off-by: Bingzhe Cai <bingzhec@codeaurora.org>
Signed-off-by: Sudhakar Manapati <smanap@codeaurora.org>