linux(4): Handle cas failure on ll/sc operations

Follow the 11a6ecd4. Check and handle the case when the ll/sc casu fails
even when the compare succeeds.

For more details PR/263825, https://reviews.freebsd.org/D35150.

Obtained from: Andrew@
MFC after: 2 weeks

(cherry picked from commit 2cd662064a0cd8d179cbb5a06378fce0ec458747)