input: atmel_mxt_ts: Add retry mechanism for I2C read/write

Try up to 3 times for each I2C read/write with 25ms delay between retries.
This is especially needed when writing to T7 to wake up the controller
from deep sleep mode.
Read/write T7 object in block, instead of one byte at a time.

Change-Id: Ibca9cdbf38c5726af5ff4ee9f0ce9ea6f0d183ee
Signed-off-by: Jing Lin <jinglin@codeaurora.org>