Input: atmel_mxt_ts - don't try to free unallocated kernel memory

If the user attempts to update Atmel device with an invalid configuration
cfg file, error handling code is trying to free cfg file memory which is
not allocated yet hence results into kernel crash.

This patch fixes the order of memory free operations.

Signed-off-by: Sanjeev Chugh <sanjeev_chugh@mentor.com>
Fixes: a4891f10 ("Input: atmel_mxt_ts - zero terminate config firmware file")
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>