Proper fix for ticket #3085 (oscam crashing).

Its a little bit of mistery why the code is not crashing on x86/x86_64
because it does exactly the same as STBs.

If mg-encrypted was not set (or properly formated), AES_decrypt()
and strtok_r() were called on a pointer to NULL because buf was
never allocated.

git-svn-id: http://streamboard.de.vu/svn/oscam/trunk@8181 4b0bc96b-bc66-0410-9d44-ebda105a78c1