Description: rsi: release skb if rsi_prepare_beacon fails 
References:
 https://github.com/torvalds/linux/commit/d563131ef23cbc756026f839a82598c8445bc45f
Notes:
 bwh> Introduced in 4.14 by commit d26a9559403c "rsi: add beacon changes for
 bwh> AP mode".
 carnil> Fixed as well in 5.3.16 and 5.4.3 already.
Bugs:
upstream: released (5.5-rc1) [d563131ef23cbc756026f839a82598c8445bc45f]
4.19-upstream-stable: released (4.19.89) [5da96cc31633a9076404621ebb89bbe78f2c8676]
4.9-upstream-stable: N/A "Vulnerable code not present"
3.16-upstream-stable: N/A "Vulnerable code not present"
sid: released (5.4.6-1)
4.19-buster-security: released (4.19.98-1)
4.9-stretch-security: N/A "Vulnerable code not present"
3.16-jessie-security: N/A "Vulnerable code not present"