Input: atmel_tsadcc - fix error handing with missing platform data

If pdata is NULL, atmel_tsadcc_probe() will release all the resources
and return 0, but we need a error code is returned in this case.
Fix to return -EINVAL and move the check for pdata to the begin
of this function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>