[media] frontends/ix2505v: Remember to free allocated memory in failure path

We may leak the storage allocated to 'state' in
drivers/media/dvb/frontends/ix2505v.c::ix2505v_attach() on error, as
it is too early to be able to call ix2505v_release().

This patch makes sure we free the allocated memory in the failure case.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>