arm64: tlbflush: Reset active_cpu on ASID rollover

[sk at gentwo.org]

Hi all,

This series is based on arm64: tlbflush: Don't broadcast if mm was only active on local cpu, specifically
on commit(s) starting from https://lore.kernel.org/linux-arm-kernel/20260523134710.3827956-1-linu.cherian@arm.com/. 

Changes since the previous posting: 
* Reset active_cpu to ACTIVE_CPU_NONE when a new ASID is assigned after rollover, so we don’t remain stuck in ACTIVE_CPU_MULTIPLE when the workload later settles back to one CPU. 
* Rely on the fact that flush_context() already issues a global TLB flush at ASID assignment after rollover, ensuring there are no stale TLB entries on any CPU. 
* This restores a fresh chance for processes to take the local-only flush fast path after each ASID generation rollover.

Series overview: 
* Patch 1/2: arm64: tlbflush: Reset active_cpu on ASID rollover 
* Patch 2/2: arm64: tlbflush: Don't broadcast if mm was only active on local cpu

Thanks,

Sayali Kulkarni 
sskulkarni at amperecomputing.com (Ampere)