Input: atmel_mxt_ts - fix bug with endianness conversion in T100 intialisation

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - leave platform to specify irqflags when using DT

The function to check the interrupt configuration must use
irq_get_trigger_type() to allow for this case.

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