Input: aiptek - adjust error-handling code label

At the point of this error-handling code, aiptek->urb has been allocated,
and it does not appear to be less necessary to free it here than in the
error-handling code just below.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>