ipaccess_recvmsg: Untangle code updating line
ipaccess_recvmsg: Untangle code updating line

This patch untangles the code a bit by changing the order where actions
are taken and variables are assigned.

The only real changes in behavour are the introduced assert, and that
bfd->data is set to NULL before releasing the related line.

Related: OS#4624
Change-Id: I947f64f8fa20f87fdc84538402623a6bcf35fdf9

osmocom/libosmo-abis,osmocom/libosmo-abis,osmocom/libosmo-abis