These flags are defined in kernel/sched/sched.h and are used when enabling/disabling migration for a task in core.c. I haven't been able to determine what SCA is short for from looking at the code or patch notes.
I spent two hours trying to dig it up from kernel's Git history and it seems the first apparition of this prefix starts from commit 9cfc3e18adb0362533e911bf3ce6ec8c821cfccc, which says :
sched: Massage set_cpus_allowed()
Thread a u32 flags word through the set_cpus_allowed () callchain. This will allow adding behavioural tweaks for future users.
I believe this is what it means.