media: dvb-frontends: delete jump targets

* Return directly after a call of the function "kzalloc" failed
  at the beginning.

* Move a bit of exception handling code into an if branch.

* Delete jump targets which became unnecessary with this refactoring.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>