apparmor: Return directly after a failed kzalloc() in two functions

1. Return directly after a call of the function “kzalloc” failed
   at the beginning in these function implementations.

2. Omit extra initialisations (for a few local variables)
   which became unnecessary with this refactoring.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: John Johansen <john.johansen@canonical.com>