Input: da9052 - fix memory leak in da9052_onkey_probe()

If, in drivers/input/misc/da9052_onkey.c::da9052_onkey_probe(), the
call to either kzalloc() or input_allocate_device() fails then we will
return -ENOMEM from the function without freeing the other allocation
that may have succeeded, thus we leak either the memory allocated for
'onkey' or the memory allocated for 'input_dev' if one succeeds and
the other fails.
Fix that by jumping to the 'err_free_mem' label at the end of the
function that properly cleans up rather than returning directly.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>