bssgp: Ensure non-NULL bctx before calling bssgp_rx_ptp (Coverity)

Currently bssgp_rx_ptp might be called with bctx being NULL, when the
NS BVCI is neither BVCI_SIGNALLING nor BVCI_PTM, but the message is
a BVC_RESET or it contains an BVCI IE != BVCI_SIGNALLING where the
BVCI is not known.

This patch ensures that bssgp_rx_ptp will only be called with a
non-NULL bctx. A log message will be issued, if the bctx is NULL when
this was not expected.

Fixes: Coverity CID 1040674
Sponsored-by: On-Waves ehf
2 files changed