Input: atmel_mxt_ts - adjust MXT_MAX_BLOCK_WRITE

Some platforms appear to have an underlying I2C device which starts corrupting
data if blocks exceed this length.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - implement support for T107 active stylus

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>