Input: atmel-wm97xx - drop unnecessary error messages

Error messages after memory allocation failures are unnecessary and
can be dropped, especially give that they were emitted as dev_dbg() so
noone except person actively debugging the driver would see them.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>