bssgp: Always expect dup != NULL in bssgp_tx_dl_ud (Coverity)

Currently the implementation of bssgp_tx_dl_ud conditionally adds
some optional IE if dup != NULL. Later on is dereferences dup to
access qos_profile and fc, but this without checking dup in advance.
This may lead to an segmentation violation fault.

This commit changes the value range of the function to only accept
dup != NULL. An assertion will fail otherwise. All other explicit
checks for non-NULL are removed.

Fixes: Coverity CID 1040673
Sponsored-by: On-Waves ehf
1 file changed